Communicate why inheriting form elements are disabled

Problem

When having disabled form inputs, it always is helpful to have a tooltip of some kind, or some other mechanism to explain to a user why a input is disabled.

As a user I feel like I'd be frustrated and confused on why I can't select the disabled option when I don't understand why it isn't usable. It isn't obvious by the change in this MR that:

If users want to edit these fields (on the project level), they need to select "Use custom settings" and override the settings manually for each project.

Comment source: !62364 (comment 583697908)

Example

Proposal

TBD by @lvanc