Support Environment credential for Azure identity - ref. original #14544

**Is your feature request related to a problem? Please describe.**
Just opening to get an update on known issue in #14544

**Describe the solution you'd like**
We heard late last year that this was being implemented and moving into identity, but we have not heard anything further. Can we get an update on this since it deals with automation and the potential to make a credential visible via the process table?

**Additional context**
All previous info should be in the prior issue here that was closed without clear path / updates: https://github.com/Azure/azure-cli/issues/14544

This is also affecting implementations of GitHub Actions that provide for az cli / az login actions such as this one: https://github.com/Azure/login/issues/27