Feature/service principal entitlement

[jgschwendswica]

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?

This PR adds the resource azuredevops_service_principal_entitlement and the data data_service_principal which have been missing so far.
This will help improve the overall automation capabilities around ADO.

Issue Number:
#1071

There's also a rather old PR addressing the same issue, however it lacks of the data part:
#1028

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

• Yes
• No

Does this introduce a breaking change?

• Yes
• No

Any relevant logs, error output, etc?

(If it’s long, please paste to https://ghostbin.com/ and insert the link here.)

Other information

[jgschwendswica]

@microsoft-github-policy-service agree company="SWICA GESUNDHEITSORGANISATION"

[xuzhang3]

Duplicate of #1028

[xuzhang3]

@jgschwendswica left some comments others looks good to me. I will take another look once these fixed.

[jgschwendswica]

@xuzhang3 thank you very much for the detailled review.
I've incorporated most of your suggested changes.
There are two leftover's where some additional inputs would be helpful

[xuzhang3]

=== RUN   TestAccServicePrincipalDataSource_Read_HappyPath
=== PAUSE TestAccServicePrincipalDataSource_Read_HappyPath
=== CONT  TestAccServicePrincipalDataSource_Read_HappyPath
--- PASS: TestAccServicePrincipalDataSource_Read_HappyPath (25.53s)
PASS
ok      github.com/microsoft/terraform-provider-azuredevops/azuredevops/internal/acceptancetests        41.932s

=== RUN   TestAccServicePrincipalEntitlement_Create
=== PAUSE TestAccServicePrincipalEntitlement_Create
=== CONT  TestAccServicePrincipalEntitlement_Create
--- PASS: TestAccServicePrincipalEntitlement_Create (12.39s)
PASS
ok      github.com/microsoft/terraform-provider-azuredevops/azuredevops/internal/acceptancetests        13.308s

[jgschwendswica]

@xuzhang3 Thank you for the detailled PR Review!
It was a very helpful since i'm Terraform heavy user, but don't have a lot of GO experience so far.
It was fun!