Add Config Override Inspector (COI).

[rosiel]

#112

This PR causes the Starter Site to have Config Override Inspector installed.

It configures the module to

• grey out (disable) the overridden form element
• display the real (override) value, unless it's marked as secret
• display a message, "This field is overridden by settings.php configuration."

It relies on the module forms including a config key which most don't. There are PRs for islandora and openseadragon to mark up the appropriate form elements, but some values we (site template) override are for search_api and matomo and they're not COI-compatible. So this will (as of now) have only a partial effect.

@Islandora-Devops/committers

[aOelschlager]

I used this to test the two COI prs (Islandora/openseadragon#57, Islandora/islandora#986)
It works!
Needs to pull in the newest commits in main and it's ready to go!