Merge the C# generator update PR in the main repo

[pakrym]

Every time we merge a change to the generator the automation runs and re-generates code in the azure-sdk-for-net repo.

Example PR: Azure/azure-sdk-for-net#12692

Sometimes code is ready to merge as is but sometimes it needs a few adjustments to get building.

Examples:

1. Export-API if public generated APIs changed. Make sure the changes are reasonable.
2. Code fixes if there were generator changes incompatible with the existing code

To make changes to the automated branch:

Do this once:

git remote add azure-sdk git@github.com:azure-sdk/azure-sdk-for-net.git
git fetch azure-sdk
git checkout -b auto-update-autorest --track azure-sdk/auto-update-autorest

Do this for every new PR:

git fetch azure-sdk
git checkout -B auto-update-autorest --track azure-sdk/auto-update-autorest
<... make changes ...>
git add .
git commit -m "..."
git push

This would update the PR with existing changes.

NOTE: Keep in mind that every merged generator change would REWRITE the branch discarding manual changes so we might need to be strategic about it.