Remove deprecated NLog.Extensions.AzureCosmosTable package (#189)

* Remove deprecated NLog.Extensions.AzureCosmosTable package source code

- Remove all source files from AzureCosmosTable (deprecated, contains vulnerabilities)
- Replace with placeholder README pointing to archive tag and migration path
- Add DEPRECATED.md with deprecation status for AzureCosmosTable and legacy bundle
- Add DEPRECATION_PROCESS.md to document deprecation workflow for future use

The package depends on WindowsAzure.Storage which is unmaintained and has known
security vulnerabilities. Users should migrate to NLog.Extensions.AzureDataTables.

Source code preserved at tag: archive/azure-cosmos-table-2022-01-29

Refs: Snyk security findings

* Update DEPRECATED.md

Co-authored-by: Copilot <[email protected]>

* Update DEPRECATION_PROCESS.md

Co-authored-by: Copilot <[email protected]>

---------

Co-authored-by: Copilot <[email protected]>

Author: JDetmar

DEPRECATED.md

@@ -0,0 +1,32 @@
+# Deprecated package: NLog.Extensions.AzureCosmosTable
+
+`NLog.Extensions.AzureCosmosTable` is deprecated, unmaintained, and contains known vulnerabilities in its dependency chain. It is no longer supported and will not receive fixes or updates.
+
+## Guidance
+
+- Do not use this package in new or existing projects.
+- Migrate to `NLog.Extensions.AzureDataTables`, which targets the supported Azure Data Tables APIs.
+- Unlist or remove any internal feeds that still carry this package to prevent accidental consumption.
+
+## Status
+
+- Maintenance: stopped
+- Security: known vulnerabilities, will not be fixed
+- NuGet: marked deprecated; recommend unlisting any remaining versions
+- Last code commit containing this package: f1c345b490a7353c5fd00d1dde42364d162173ce (2022-01-29 — see tag `archive/azure-cosmos-table-2022-01-29`)
+
+## Deprecated package: NLog.Extensions.AzureStorage (bundle)
+
+The legacy bundled package `NLog.Extensions.AzureStorage` was superseded when targets were split. It should not be used.
+
+### Guidance (bundle)
+
+- Do not use the bundled package; consume the individual packages (Blob, Queue, EventHub, EventGrid, DataTables, ServiceBus, AccessToken) instead.
+- Unlist or remove any internal feeds that still carry the bundle to prevent accidental consumption.
+
+### Status (bundle)
+
+- Maintenance: stopped
+- Security: inherits vulnerabilities from deprecated dependencies in the bundle; will not be fixed
+- NuGet: should be marked deprecated/unlisted
+- Last code commit containing this bundle: c8bfb7966d550221e1aeca859705f606c8559dd2 (tag `archive/azure-storage-bundle`)

DEPRECATION_PROCESS.md

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+# Deprecation and Removal Playbook
+
+Practical steps to deprecate and remove a package (while keeping history) without letting vulnerable code stay on the default branch or get republished.
+
+## Steps
+
+1. **Declare deprecation**
+   - Open an issue/PR stating the reason (vulnerability/abandonment) and affected package name.
+   - Add a loud banner to the package README and a short note in the root README pointing to the safer alternative.
+   - Add/update `DEPRECATED.md` with the status and migration guidance.
+
+2. **Stop distribution**
+   - Remove the project from the solution and CI pack/test pipelines so it cannot be built or packed.
+   - Unlist all NuGet versions, or publish a final version with release notes that say "deprecated, insecure, unsupported" and link to the alternative.
+   - Verify no other packages in the repo reference it (remove references or add a compile-time `#error` guard if needed).
+
+3. **Clean the default branch for scanners**
+   - Delete the package source folder from `master` (or default branch) and replace it with a small placeholder README that states it was removed, why, and where to find an alternative.
+   - Keep a brief note in the root README so users understand it was intentionally removed.
+
+4. **Preserve history without branch sprawl**
+   - Tag the last commit that still contained the code (e.g., `archive/<package>-YYYY-MM-DD`).
+
+5. **Security and comms**
+   - If the risk is security-related, add a short SECURITY/Advisory note: status = won't fix, remediation = use alternative, scope of impact.
+   - Optionally pin the advisory in the repo and link it from the package README placeholder.
+
+6. **Validate**
+   - Run `dotnet build` and targeted tests to confirm removal did not break supported packages.
+   - Confirm CI pack/test steps skip the removed package.
+
+## Artifacts to touch (typical)
+
+- Package README: banner + deprecation note or placeholder.
+- Root `README.md`: short note and link to alternative.
+- `DEPRECATED.md`: status and guidance.
+- Solution file and CI config: remove project, pack, and test entries.
+- Optional: SECURITY/advisory file with "won't fix" language.
+
+## Templates
+
+**Placeholder README snippet (in the removed package folder):**
+
+```markdown
+# <PackageName> (removed)
+
+This package was removed from the default branch because it is deprecated and contains known vulnerabilities. It is unmaintained and should not be used. See <AlternativePackage> instead.
+
+Last code version is preserved at tag: archive/<package>-YYYY-MM-DD.
+```
+
+**Release notes snippet for the final/last package version:**
+
+```text
+Deprecated and insecure. This package is unmaintained and contains known vulnerabilities. Do not use. Migrate to <AlternativePackage>.
+```
+
+## Quick command hints
+
+- Tag the last commit before removal:
+
+```sh
+git tag archive/<package>-YYYY-MM-DD
+```
+
+
+- Remove a project from the solution (example):
+
+```sh
+dotnet sln src/NLog.Extensions.AzureStorage.sln remove src/<Project>/<Project>.csproj
+```
+
+## Checklist for each deprecation
+
+- [ ] Banner in package README + root README note
+- [ ] Solution/CI pack/test entries removed
+- [ ] NuGet versions unlisted or final deprecated version published with clear notes
+- [ ] Placeholder README in default branch, code removed
+- [ ] Tag created for last code commit (and archive branch if required)
+- [ ] Advisory/SECURITY note added when security-driven
+- [ ] Build/tests rerun to verify unaffected packages