Incorporate `msrestazure`'s code for managed identity authentication

[jiasli]

Related command

az login --identity

Is your feature request related to a problem? Please describe.

Managed identity has lots of variations in different services (VM, app service, Azure Arc, hybrid runbook). Each variation requires special handling.

There are feature requests to support new types of managed identities:

• Support az login --identity for Azure Arc #16573
• Support Linux Hybrid Runbook Worker VM's Managed Identity #22243

But there are some technical difficulties:

• Azure CLI dropped Azure Identity and now directly uses MSAL for user/service principal authentication
• Currently, Azure CLI uses msrestazure for managed identity authentication, but msrestazure has been replaced by Azure Identity and out of maintainance
• MSAL has no managed identity support, and it is not planed in the near future (Support Managed Identity (formerly known as MSI) AzureAD/microsoft-authentication-library-for-python#58)

Describe the solution you'd like

In order to support new variations of managed identity, Azure CLI needs to incorporate msrestazure's code and make changed on top of that.

Describe alternatives you've considered

MSAL to support managed identity.

[yonzhan]

managed identity authentication

[jiasli]

This issue is superseded by #25860 as MSAL is going to support managed identity (AzureAD/microsoft-authentication-library-for-python#480), so Azure CLI will use MSAL for managed identity authentication in the future.