workflows: Add permissions.

[Javagedes]

Add permissions to the workflows across mu_devops. This includes the workflows sync'd across repositories, and workflows used in mu_devops itself.

With MU_BASECORE's Settings -> Code and automation -> Actions -> General -> Workflow permissions set to "Read repository contents and packages permissions" selected, I had no failures, with the following tested:

.github/workflows

• AutoMerger.yml - Untested
• FileSyncer.yml - Tested
• IssueAssignment.yml - Tested
• IssueTriager.yml - Tested
• LabelSyncer.yml - Tested
• Labeler.yml - Tested
• ReleaseDrafter.yml - Tested

.sync/workflows/leaf

• auto-approve.yml - Untested
• auto-merge.yml - Untested
• issue-assignment.yml - Tested through IssueAssignment.yml
• label-issues.yml - Tested through Labeler.yml
• label-sync.yml - Tested through LabelSyncer.yml
• pull-request-formatting-validator.yml - Tested Directly
• release-draft.yml - Tested through ReleaseDrafter.yml
• scheduled-maintenance.yml - Tested Directly
• stale.yml - Tested Directly
• submodule-release-update.yml - Untested
• triage-issues.yml - Tested