fix: #3624663 Indicate in form error messages when error is sidebar

Tiagorequested to merge
issue/drupal-3624663:3624663-indicate-in-form into main

Closes #3624663

Adds an "Open the sidebar" button to the error messages of fields in the sidebar when Inline Form Errors is not installed. The button opens the sidebar and focuses the field. It is hidden while the sidebar is open.

Also fixes the sidebar collapsing again below 1024px on any height change of the page: the ResizeObserver now only reacts to width changes.

Tests: AdminNodeTest (functional) and a new SidebarErrorMessagesTest (functional JavaScript).

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