Issue #2957425 by tedbow, johndevman, tim.plunkett, hawkeye.twolf, Berdir, alexpott, samuel.mortenson, kevincrafts, jibran, larowlan, amateescu, twfahey, sjerdo, mtodor, japerry, xjm, phenaproxima, mglaman, EclipseGc, johnzzon: Allow the inline creation of non-reusable Custom Blocks in the layout builder

(cherry picked from commit 500403b4)

Issue #2936358 by tim.plunkett, johndevman, tedbow, eiriksm, AaronMcHale, phenaproxima, pookmish, alexpott: Layout Builder should be opt-in per display (entity type/bundle/view mode)

(cherry picked from commit c6cdc439)

Issue #2950892 by tim.plunkett, guile2912, tedbow: Exceptions thrown during Layout Builder preview are not caught

Issue #2937799 by EclipseGc, tim.plunkett, effulgentsia, tedbow, Kristen Pol: Allow greater flexibility within SectionComponent::toRenderArray()

Issue #2937483 by tim.plunkett, larowlan, EclipseGc, samuel.mortenson: Defining a new type of section storage relies on magic strings and hidden assumptions

Issue #2922033 by tim.plunkett, mtodor, larowlan, xjm, pameeela, EclipseGc, samuel.mortenson: Use the Layout Builder for EntityViewDisplays

Issue #2928450 by tim.plunkett: Remove dead code in the Layout Builder following Section refactoring

Issue #2905922 by tim.plunkett, tedbow, xjm, EclipseGc, webchick, vijaycs85, larowlan, andrewmacpherson, droplet, Bojhan, mgifford, drpal, phenaproxima, DyanneNova, japerry: Implementation issue for Layout Builder

Revert "Issue #2905922 by tim.plunkett, xjm, EclipseGc, vijaycs85, webchick, larowlan, andrewmacpherson, Bojhan, droplet, mgifford, drpal, japerry, tedbow, DyanneNova, phenaproxima: Implementation issue for Layout Builder"

This reverts commit 88a22dda.

Issue #2905922 by tim.plunkett, xjm, EclipseGc, vijaycs85, webchick, larowlan, andrewmacpherson, Bojhan, droplet, mgifford, drpal, japerry, tedbow, DyanneNova, phenaproxima: Implementation issue for Layout Builder