If a site only supports a 'throbber' for progress, don't show a summary or gear icon

Problem/Motivation

I originally reported this at #2113931-236: File Field design update: Upload field. → .B:

When I went to configure the widgets on "Manage form display", I noticed a minor UI WTF. The summary says "Progress indicator: throbber" but when I click on the gear icon to see what the other choices are and try them out, there's no setting at all. :/ I guess that's supposed to be at 📌 File Field design update progress bar Active or something, but until that lands, it seems a little cruel and a lot confusing to advertise the "throbber" as a widget option if I can't change it. ;) Can we just rip that out from the settings summary and add it back in once there's a setting we can change that needs to be summarized?

Summary:

Empty widget settings:

I then discovered it has nothing to to with that patch nor 📌 File Field design update progress bar Active , but instead my local dev site didn't have uploadprogress.so enabled. ;)

Splitting this off as a minor UX follow-up...

Note, this might be made obsolete if we get 📌 Add support for built-in PHP session upload progress Needs work working and all sites will always have a bar option available and file_progress_implementation() always returns something (or goes away entirely?).

Proposed resolution

If file_progress_implementation() returns FALSE, theres's no progress bar implementation available, and we only support a throbber, don't show a summary for the progress indicator and don't show a gear icon when configuring a file widget.

Remaining tasks

TBD.

User interface changes

Hide the gear icon and settings summary for field field widget on sites that don't allow you to configure the progress indicator at all.

API changes

Probably none.

Data model changes

None.

Release notes snippet

TBD.