Provide tooling to better support _shared folders

[petrsvihlik]

Is your feature request related to a problem? Please describe.
In azure-communication, we use the _shared folder pattern to avoid dependency conflicts. With the increasing number of ACS packages, it's more and more difficult to maintain it. Also, there are new people being onboarded to ACS all the time who are not aware of this convention which makes it even more difficult to keep the folders in sync.

We see three problems:

1. It's a tedious job to update all copies of the _shared folder when introducing a change in them (more copies == more work)
2. People forget to do so (==> inconsistencies)
3. People don't always run all the related pipelines (==> broken builds). Typically, I'd like to run all live test pipelines python - azure-communication-* - tests

Affected services
We know of at least the following three:

• Communication - https://github.com/Azure/azure-sdk-for-python/tree/main/sdk/communication/azure-communication-identity/azure/communication/identity/_shared
• Storage - https://github.com/Azure/azure-sdk-for-python/tree/main/sdk/storage/azure-storage-blob/azure/storage/blob
• Key Vault - https://github.com/Azure/azure-sdk-for-python/tree/main/sdk/keyvault/azure-keyvault-secrets/azure/keyvault/secrets/_shared

Describe the solution you'd like
List of problems ordered by priority and proposed solutions:

• Problem no. 2 could be perhaps solved by a pipeline check that would prevent a PR being merged without pipelines being in sync.
• Problem no. 3 is harder to solve optimally as not all shared code is used by all modalities so we'd have to run some code analysis to determine which pipelines to run. But generally speaking, we could run all azure-communication pipelines if we detect a change in a _shared folder. This could, however, cause the PR to be unmergable because many of the pipelines are often broken (that's the reality).
• Problem no. 1 could be solved by a shell script something like Sync-Shared-Folders.ps1

Describe alternatives you've considered

1. As a temporary prevention of the problem no. 2, we introduced new rules in the CODEOWNERS file to keep the _shared folder protected.
2. To address problems 1 & 2, we experimented with symlinks - Symlink experiment for _shared folder #28021

Additional context

• Teams discussion

[annatisch]

Adding the messaging crew as this will also have an impact in keeping _pyamqp in sync between ServiceBus and EventHubs
cc @kashifkhan, @swathipil, @LibbaLawrence

[github-actions]

Hi @petrsvihlik, we deeply appreciate your input into this project. Regrettably, this issue has remained unresolved for over 2 years and inactive for 30 days, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.