Add Service Principal Authentication methods

[davidcorrigan714]

All Submissions:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code follows the code style of this project.
• I ran lint checks locally prior to submission.
• Have you checked to ensure there aren't other open PRs for the same update/change?

What about the current behavior has changed?

Allows the terraform provider to authenticate to azure devops through a service principal using a variety of authentication methods: client secret, client certificate, GitHub Actions OIDC tokens, Terraform Cloud OIDC tokens, & any other OIDC token provided directly as an attribute

Does this introduce a change to go.mod, go.sum or vendor/?

• Yes
• No

Brings in the Azure Go SDK & some crypto libraries.

Does this introduce a breaking change?

• Yes
• No

[irwand]

the description has "No" checked on "brings in crypto library" but I think you are bringing crypto library, right?

[davidcorrigan714]

the description has "No" checked on "brings in crypto library" but I think you are bringing crypto library, right?

Whoops, missing a question header there from the template. Fixed to indicate no breaking changes.