Adding Azure.Functions.Cli.TestFramework.csproj to have E2E tests run on

[aishwaryabh]

Issue describing the changes in this PR

resolves #4327

This PR is the second part of a series of PRs to set up a new testing framework for the Azure Functions CLI. This is the larger PR, which contains all the changes for the testing framework and the updated func start E2E test, if you would like to take a look at how it all fits in! I just decided to split it up since it would be easier to review and get feedback this way.

Func.TestFramework.csproj contains the new test framework that can be used for the E2E tests or even unit tests. FuncCommand is the base class that implements Command defined in the abstractions project. For debugging purposes, I also create a file for each FuncCommand created and dump the logs that are defined into the file. These logs are then published as an artifact in a folder called TestLogs, which can be useful for debugging in the future (the last step of publishing the logs will be in the final PR)!

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• I have added all required tests (Unit tests, E2E tests)

[liliankasem]

Honesty you can probably just drop E2E Tests PART x: from these PR names, or at least please remove them from the commit message when you squash-merge :)