Issue #3627004: Frontend builder formatter does not work on displays that use Layout Builder.

Fixes #3627004. Related: #3522459.

Three commits, one per problem, each with its tests so they can be reviewed or split:

1. The formatter resolves the view mode from the layout_builder third party setting instead of the _custom placeholder, and leaves out the edit link (with a warning) when it cannot be resolved.
2. close() passes display options instead of a view mode name, so closing the builder no longer replaces the field with nothing on Layout Builder displays.
3. buildForm() throws NotFoundHttpException unless the resolved renderer is a LayoutParagraphsBuilderFormatter.

New Kernel test: LayoutBuilderCompatibilityTest. Without the fix 6 of its 7 tests fail (the seventh is a control). With it all pass, together with the existing InsertIntoRegionDeltaTest.

Applies cleanly to 3.0.x (ca8405cc). The same diff also applies to 2.1.x.