Eng workflows sync and branch cleanup additions

[JimSuplizio]

Changes so we can sync .github/workflows the same way we're doing with eng/common.

1. eng/pipelines/eng-workflows-sync.yml - similar to eng/pipelines/eng-common-sync.yml except this does the .github/workflows directory. The common code was already factored out into a template, eng/pipelines/templates/stages/archetype-sdk-tool-repo-sync.yml as part of this PR. Once this has been merged a pipeline will need to be created from this.
2. eng/pipelines/branch-cleanup.yml - updated to add Azure/azure-sdk to the list of repositories and a second task was added to clean up "sync-.github/workflows" branches.
3. doc/workflows/engsys_workflows.md - similar to doc/common/common_engsys.md, which describes the purpose and workflow of updating the .github/workflows directory.
4. eng/common/pipelines/templates/steps/eng-common-workflow-enforcer.yml - It wasn't clear if we wanted a second enforcer or another if statement in the current one. I went with the if statement which shouldn't require anything else in the target repositories.
5. eng/common/scripts/Delete-RemoteBranches.ps1 - The only actual change here is an additional comment on line 13 to add the regex for sync-.github/workflows work.

[azure-sdk]

The following pipelines have been queued for testing:
java - template
java - template - tests
js - template
net - template
net - template - tests
python - template
python - template - tests
You can sign off on the approval gate to test the release stage of each pipeline.
See eng/common workflow