[new resource] - azuredevops_serviceendpoint_nuget

[xuzhang3]

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?

Issue Number: #776

=== RUN   TestAccServiceEndpointNuGet_ApiKey
=== PAUSE TestAccServiceEndpointNuGet_ApiKey
=== RUN   TestAccServiceEndpointNuGet_PersonalAccessToken
=== PAUSE TestAccServiceEndpointNuGet_PersonalAccessToken
=== RUN   TestAccServiceEndpointNuGet_UnamePwd
=== PAUSE TestAccServiceEndpointNuGet_UnamePwd
=== RUN   TestAccServiceEndpointNuGet_Update
=== PAUSE TestAccServiceEndpointNuGet_Update
=== RUN   TestAccServiceEndpointNuGet_RequiresImportErrorStep
=== PAUSE TestAccServiceEndpointNuGet_RequiresImportErrorStep
=== CONT  TestAccServiceEndpointNuGet_ApiKey
=== CONT  TestAccServiceEndpointNuGet_Update
=== CONT  TestAccServiceEndpointNuGet_UnamePwd
=== CONT  TestAccServiceEndpointNuGet_RequiresImportErrorStep
=== CONT  TestAccServiceEndpointNuGet_PersonalAccessToken
--- PASS: TestAccServiceEndpointNuGet_PersonalAccessToken (64.71s)
--- PASS: TestAccServiceEndpointNuGet_ApiKey (65.16s)
--- PASS: TestAccServiceEndpointNuGet_UnamePwd (65.27s)
--- PASS: TestAccServiceEndpointNuGet_RequiresImportErrorStep (75.14s)
--- PASS: TestAccServiceEndpointNuGet_Update (84.35s)
PASS
ok      github.com/microsoft/terraform-provider-azuredevops/azuredevops/internal/acceptancetests        95.786s

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