move pre cleanup to main and add pre-if and post-if

[YanaXu]

This PR is going to fix #426.

What are in this PR

• Remove pre step from Azure Login Action and add the "pre cleanup" to main step.
• Add an env variable AZURE_LOGIN_PRE_CLEANUP for checking if "cleanup before login" is necessary. By default, "cleanup before login" is disabled, only when AZURE_LOGIN_PRE_CLEANUP is set and is "true", "cleanup before login" will be run.
• Add an env variable AZURE_LOGIN_POST_CLEANUP for checking if "post cleanup" is necessary. By default, "post cleanup" is enabled.

Description of the issues we know about

1. If Azure CLI, PowerShell or Azure PowerShell are not pre-installed on runner but installed in the steps of the workflow, an warning will be thrown in the pre step. E.g., "ephemeral self-hosted runners" as metioned in #426.

• It'll be fixed in this PR since pre step will be removed.

2. pre cleanup or post cleanup are not necessary for GitHub-hosted runners since they are always clean.

• After this PR, by default, there is no pre cleanup in a job.
• post cleanup does no harm. But it's also OK if users set env AZURE_LOGIN_POST_CLEANUP to false to skip post cleanup in case of GitHub-hosted runners.

3. If Azure Login Action runs multiple times in a job, there will be multiple pre and post steps.

• After this PR, there are no pre steps.
• Multiple post cleanup steps are not necessary. Users can set env AZURE_LOGIN_POST_CLEANUP to true for only one Azure Login Action step and set env AZURE_LOGIN_POST_CLEANUP to false for all other Azure Login Action steps.

4. If there is a if in Azure Login Action and it doesn't match, Azure Login Action will be skipped but the pre step will still run.

• It'll be fixed in this PR since pre step will be removed.

5. Composite Action does not support pre step and will throw an warning.

• It'll be fixed in this PR since pre step will be removed.
• post step will work well.

6. Local Action (checkout the aciton and run it) does not support pre step and will throw an warning.

• It'll be fixed in this PR since pre step will be removed.
• post step will work well.

Reference

• Composite Action does not support pre step: Support pre and post steps in Composite Actions actions/runner#1478
• Local Action does not support pre step: Warning: pre execution is not supported for local action from './' actions/typescript-action#564
• Azure Login Action should not clear context during a job refer to this issue v1.5.1 breaks multi subscription login #383

How to use

    - name: Azure Login
      uses: azure/login@v2
      env:
        AZURE_LOGIN_PRE_CLEANUP: false
        AZURE_LOGIN_POST_CLEANUP: false
      with:
        client-id: ${{ secrets.CLIENT_ID }}
        tenant-id: ${{ secrets.TENANT_ID }}
        subscription-id: ${{ secrets.SUBSCRIPTION_ID }}
        enable-AzPSSession: true

[HowardvanRooijen]

Thank you!