[Batch] Rollback the support for TokenCredential

[deyaaeldeen]

Batch has been advertising using shared keys as their primary way of authentication in their docs. #16679 added support for TokenCredential authentication but it turned out that batch is not compatible with the support for token credentials in @azure/ms-rest-js because the latter assumes a scope that only works with management-plane libs.

If we want to fix the support for AAD, we will have to add support for custom scopes in @azure/ms-rest-js so we can pass the batch scope https://batch.core.windows.net//.default to it and also update azureTokenCredential as follows:

azureTokenCredential.msalFlow.identityClient.authorityHost = "https://login.microsoftonline.com/<tenant id>";
azureTokenCredential.msalFlow.identityClient.baseUri = "https://login.microsoftonline.com/<tenant id>";
azureTokenCredential.msalFlow.tenantId = "<tenant id>";

Because of the hassle of doing the fix and the fact that AAD support was not advertisied in batch to begin with, we want to go ahead and revert the support for TokenCredential instead.

[ramya-rao-a]

What is the benefit of showing the Azure CLI option over the API key one? Can we skip this and showcase the API key scenario as that is what is shown in the official samples as well?

[deyaaeldeen]

This was the readme used earlier, so I kept them to show case how to use nodeauth. To address your feedback, I deleted the CLI one and kept the shared key and the other nodeauth one.

[deyaaeldeen]

@ramya-rao-a please take a look now.