Issue #2822382 by voleger, pfrenssen, erozqba, RytoEX, borisson_, sidharthap, Jo Fitzgerald, shashikant_chauhan: Make every  property protected on classes extending BrowserTestBase and KernelTestBase

(cherry picked from commit 69501f30)

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