Add guidelines for granting maintainer access to the Quality handbook

Why is this change being made?

We should have some criteria and guidelines in place about when a Quality team member is ready to be granted maintainer access to various projects.

Additionally, while looking for a place to add this information I discovered that the GPT was still referred to as the "Toolkit" in our handbook and not the "Tool". I made those updates in a commit on this branch too.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what