New/Set-GitHubRepository: Add Support for `Allow Auto Merge` Option

[X-Guardian]

Feature Idea Summary

GitHub have added a new option 'Allow Auto Merge' to Repositories that could be added to the New-GitHubRepository and Set-GitHubRepository Cmdlets.

Feature Idea Additional Details

References:

• Automatically Merging a Pull Request

API Reference

• https://docs.github.com/en/rest/repos/repos#create-an-organization-repository
• https://docs.github.com/en/rest/repos/repos#update-a-repository

Parameters

• allow_auto_merge

Requested Assignment

• If possible, I would like to implement this.

[HowardWolosky]

Sounds good. Thanks for bringing this up and coding the fix!

[HowardWolosky]

Re-opening as the change was reverted for two reasons:

1. AllowAutoMerge was not working on Set-GitHubRepository (appears to be a bug on the GitHub side, but I was simply unable to validate that the feature worked)
2. use_squash_pr_title_as_default has been deprecated and is also not being respected in my tests. It appears that we need to migrate over to squash_merge_commit_title instead, which has different usage.