Setting only_allow_merge_if_all_discussions_are_resolved on a project

[CaseyMacPherson]

Need to be able to set this property on a project.

In all instances the current project or the updated project is returned

-OnlyAllowMergeIfAllDiscussionsAreResolved

Get-GitlabProject | Update-GitlabProject -OnlyAllowMergeIfAllDiscussionsAreResolved -Whatif
What if: Performing the operation "update project ({
  "only_allow_merge_if_all_discussions_are_resolved": {
    "IsPresent": true
  }
})" on target "notimportant".

-OnlyAllowMergeIfAllDiscussionsAreResolved:$false

Get-GitlabProject | Update-GitlabProject -OnlyAllowMergeIfAllDiscussionsAreResolved:$false -Whatif
Nothing to update

-OnlyAllowMergeIfAllDiscussionsAreResolved:$true

Get-GitlabProject | Update-GitlabProject -OnlyAllowMergeIfAllDiscussionsAreResolved:$true Whatif
What if: Performing the operation "update project ({
  "only_allow_merge_if_all_discussions_are_resolved": {
    "IsPresent": true
  }
})" on target "notimportant".

No switch specified

Get-GitlabProject | Update-GitlabProject -Whatif
Nothing to update