Issue #2866810 by BrightBold, harsha012, joelpittet: Update stylelint rule function-comma-space-after to be consistent with Drupal's CSS standards

Issue #2793207 by SKAUGHT, Yogesh Pawar, Mukeysh, Cottser, webchick, tkoleary, alexpott: Fix off-set and goofy white jagged background of AJAX throbber when clicking Place Block

Issue #2795539 by Shashwat Purav, shashikant_chauhan: Punctuation issue for Place block module in hook_help

Issue #2739079 by DyanneNova, akalata, webchick, tkoleary, pwolanin, SKAUGHT, elliotc, lizzjoy, YesCT, yoroy, miwayha: Create a validated design for Block Place module

(cherry picked from commit e5824c36)

Issue #2791335 by pwolanin: Optimize repeated method call in  PlaceBlockPageVariant::build, use service instead of direct query string

Issue #2724819 by SKAUGHT, pwolanin, tim.plunkett, tkoleary, tedbow, webchick, yoroy, Wim Leers, brantwynn, Bojhan: Create experimental module for place block on any page feature