Add support for Managed Identity

[JoshLozensky]

Add support for Managed Identity

Added ManagedIdentity as a CredentialType

Description

Added Managed Identity to the Credential Type, Description, and Source classes. Created a new class ManagedIdentityOptions with the three relevant fields ClientId, ObjectId, and HostResourceId

Fixes #1775 #2551

[jmprieur]

The design is to have a property of type ManagedIdentityOptions on AcquireTokenOptions, not to change CredentialSource/CredentialDescription

[jmprieur]

Thanks @JoshLozensky

There are a few things to change, but this looks good already!

[jmprieur]

@JoshLozensky
this is a really good proposal!

I'm still hesitant about the verbosity. I personally prefer shorter expressions, and a pay as you go approach: I want to use managed identity, but default it's a system assigned one, so I'll just say "Managed identity". then if I've made more effort and created a user-assigned managed identity I know the client ID and I can provide the ID.

For the programmatic approach, static methods:

ManagedIdentityDescription.FromUserAssignedObjectId(string) etc, could also help.

[bgavrilMS]

I agree with @jmprieur 's proposals. Will review again once those are taken into consideration.

PS: naming is hard. we had endless discussions about this in MSAL .NET and MSAL JS as well.

[jmprieur]

LGTM
Thanks @JoshLozensky

[jennyf19]

using System;

license info needs to be added for all new files.

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Refers to: src/Microsoft.Identity.Abstractions/ManagedIdentity/ManagedIdentityType.cs:1 in 11fde20. [](commit_id = 11fde20, deletion_comment = False)

[jennyf19]

using System;

are all the usings needed?

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In reply to: 1835478327

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Refers to: src/Microsoft.Identity.Abstractions/ManagedIdentity/ManagedIdentityType.cs:1 in 11fde20. [](commit_id = 11fde20, deletion_comment = False)

[jmprieur]

LGTM
Thanks @JoshLozensky

A few more fixes to do (per the compiler)

[jennyf19]

Approving as @JoshLozensky and I discussed offline on the few remaining comments.