Sync eng/common directory with azure-sdk-tools for PR 12060 (#3026)

Sync eng/common directory with azure-sdk-tools for PR
Azure/azure-sdk-tools#12060 See [eng/common
workflow](https://github.com/Azure/azure-sdk-tools/blob/main/eng/common/README.md#workflow)

---------

Co-authored-by: catalinaperalta <[email protected]>
Co-authored-by: ray chen <[email protected]>
Co-authored-by: Mike Harder <[email protected]>

Author: 4 people

eng/common/tsp-client/README.md

@@ -0,0 +1,79 @@
+# TypeSpec Client Generator CLI
+
+This directory contains npm package definitions for `@azure-tools/typespec-client-generator-cli` (tsp-client) with pinned versions to ensure reproducible builds across environments.
+
+## Files
+
+- **`package.json`** - npm package definition with pinned tsp-client version
+- **`package-lock.json`** - Lock file ensuring exact dependency versions
+
+## Prerequisites
+
+- **Node.js** (with npm) - Required to install and run tsp-client
+
+## Installation
+
+### Install dependencies
+
+```bash
+# Navigate to this directory
+cd eng/common/tsp-client
+
+# Install dependencies
+npm ci
+
+## Usage
+
+After installation, you can run tsp-client by navigating to the directory and using npm exec:
+
+```bash
+cd eng/common/tsp-client
+
+# Get help
+npm exec --no -- tsp-client --help
+
+# Check version
+npm exec --no -- tsp-client version
+
+# Generate client code
+npm exec --no -- tsp-client generate --output-dir ./generated
+
+# Initialize a new project
+npm exec --no -- tsp-client init --tsp-config ./tspconfig.yaml
+```
+
+## CI/CD Best Practices
+
+```bash
+cd eng/common/tsp-client
+npm ci
+npm exec --no -- tsp-client init --update-if-exists --tsp-config https://github.com/Azure/azure-rest-api-specs/blob/dee71463cbde1d416c47cf544e34f7966a94ddcb/specification/contosowidgetmanager/Contoso.WidgetManager/tspconfig.yaml
+```
+
+## Package Management
+
+### Automatic Updates via Dependabot
+
+Dependabot is configured to automatically check for updates to `@azure-tools/typespec-client-generator-cli` daily and create pull requests with updated `package.json` and `package-lock.json` files. This ensures the package stays current with the latest versions while maintaining security through the PR review process.
+
+### Manual Version Updates
+
+If you need to manually update the tsp-client version:
+
+1. Edit `package.json` to update the version:
+
+   ```json
+   {
+     "dependencies": {
+       "@azure-tools/typespec-client-generator-cli": "0.8.0"
+     }
+   }
+   ```
+
+2. Update the lock file:
+
+   ```bash
+   npm install
+   ```
+
+3. Commit both `package.json` and `package-lock.json`