feat: Add ListProvisionedScimGroupsForEnterprise inside SCIM service with test

[cyberious]

This pull request introduces several enhancements to the SCIM (System for Cross-domain Identity Management) functionality in the github/scim.go file. The key changes include the addition of new types to represent SCIM group attributes and provisioned groups, as well as a new method to list provisioned SCIM groups for an enterprise. Additionally, a corresponding test function has been added to ensure the correctness of the new method.

Enhancements to SCIM functionality:

• Added SCIMGroupAttributes type to represent supported SCIM group attributes, including DisplayName, Members, Schemas, ExternalID, ID, and Meta. ([github/scim.goR20-R38](https://github.com/google/go-github/pull/3467/files#diff-c2dda2100fd0c700da11a5d96582391b4923658db7e717627d248ae1c029c5fbR20-R38))
• Introduced SCIMProvisionedGroups type to represent the result of calling ListSCIMProvisionedIdentities, including Schemas, TotalResults, ItemsPerPage, StartIndex, and Resources. ([github/scim.goR78-R86](https://github.com/google/go-github/pull/3467/files#diff-c2dda2100fd0c700da11a5d96582391b4923658db7e717627d248ae1c029c5fbR78-R86))
• Added ListProvisionedScimGroupsForEnterprise method to list provisioned SCIM groups for an enterprise, including the necessary API documentation reference. ([github/scim.goR248-R269](https://github.com/google/go-github/pull/3467/files#diff-c2dda2100fd0c700da11a5d96582391b4923658db7e717627d248ae1c029c5fbR248-R269))

Testing:

• Added TestSCIMService_ListSCIMProvisionedGroups function to test the new ListProvisionedScimGroupsForEnterprise method, ensuring it handles responses correctly and validates various scenarios. ([github/scim_test.goR124-R217](https://github.com/google/go-github/pull/3467/files#diff-2723dd506a61e0f7abe849217ded7c4aa5dfef10455f14ed10a423c65f4dac49R124-R217))

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.04%. Comparing base (ce42642) to head (3781247).
Report is 1 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #3467 +/- ##
=======================================
Coverage 91.03% 91.04% =======================================
Files 179 179 Lines 15538 15551 +13 =======================================
+ Hits 14145 14158 +13 
Misses 1221 1221 Partials 172 172 

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[gmlewis]

Please run step 4 of CONTRIBUTING.md and push the results (./script/generate.sh, ./script/lint.sh, and ./script/test.sh).

[cyberious]

@gmlewis updated it. I apologize for not seeing that earlier.

Squashed into the same commit

[gmlewis]

Just FYI - As described in CONTRIBUTING.md, there is no need to force-push in this repo, as we always squash-and-merge so that the commit history is clean. In fact, we discourage it because it makes it more challenging for reviewers to see what changed since their last review.
However, for this tiny PR, it really makes no difference, so no big deal... but just wanted to let you know in case you make larger PRs in the future, which are totally welcome. 😄 ❤️

[gmlewis]

Thank you, @cyberious !
One minor tweak, please, then awaiting second LGTM+Approval from any other contributor to this repo before merging.

[gmlewis]

Thank you, @cyberious !
LGTM

Awaiting second LGTM+Approval from any other contributor to this repo before merging.

@stevehipwell - might you have time for a code review? Thank you!

[stevehipwell]

Minor nit/question.

[stevehipwell]

LGTM

[gmlewis]

Thank you, @cyberious and @stevehipwell !
LGTM
Merging.