Add feature-test coverage for Rich Text Field

[seanpdoyle]

Follow-up to #2411

Add Capybara-driven feature test coverage for filling in and rendering the contents of a <trix-editor> element.

[pablobm]

Just a minor comment.

[pablobm]

Ah, just 0.1 requirements of a version away from doing away with this part 😄 I wonder if we should drop support for 6.* now that they have been EOL'd (https://rubyonrails.org/2024/10/15/new-maintenance-policy-and-eol-annouments). Thoughts, @nickcharlton?

But since this is here and solved for now, I think it's not a blocker. We can decide about Rails requirement separately.

[nickcharlton]

This is perhaps a separate discussion, but I wonder if we can drop support post-1.0 (1.1?).

I don't want 1.0 to be so big that it means people avoid upgrading (which is a good argument to call it in the next few weeks?), then drop it on the next release. It's a bit similar to how Apple does it with macOS.