Issue #2972153 by dimitriskr, alexpott, smustgrave, andypost, kostyashupenko: Deprecate ThemeHandlerInterface::getBaseThemes and remove usages from core

Issue #2942001 by dimitriskr, alexpott, gaurav.kapoor, smustgrave, andypost, almaudoh: Deprecate ThemeHandlerInterface::rebuildThemeData() and use extension.list.theme service instead

Issue #3324838 by Spokje: Fix PHPStan L2 error "PHPDoc tag @throws with type Foo is not subtype of Throwable"

Issue #3304256 by longwave, Spokje, dww, lauriii, catch, quietone, mherchel: Remove Bartik from Drupal core

Issue #2776031 by fgm, andypost, voleger, yogeshmpawar, Berdir, joachim: Properly deprecate ThemeHandlerInterface install() and uninstall() also replace usage

Issue #2659940 by almaudoh, alexpott, phenaproxima, Jo Fitzgerald, markcarver, oriol_e9g, dawehner, dsnopek, jibran, larowlan: Extension System, Part III: ThemeExtensionList and ThemeEngineExtensionList

Issue #2901730 by mfernea, ankitjain28may, idebr: Fix 'Squiz.WhiteSpace.FunctionSpacing' coding standard

Issue #2882784 by harsha012, douggreen, joelpittet: Fix ThemeHandlerInterface::setDefault() deprecation code example in header comment

Issue #2635784 by Manuel Garcia, sidharthap, cilefen, veerasekar89, gambry, catch, alexpott, Cottser, dawehner, joelpittet: Deprecate ThemeHandler::setDefault() in favour of configuration and replace usages

Issue #2708179 by anoopjohn: Fix 'Drupal.Commenting.FunctionComment' coding standard - Issues related to @throws

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2574975 by alexpott, Cottser, izus: Allow (base-)themes to be excluded from the UI (e.g. blocks, Appearance)

Issue #2499615 by honzakuchar: Docblock interface Drupal\Core\Extension\ThemeHandlerInterface::uninstall typo

Issue #2465887 by dawehner, amateescu, tim.plunkett: Extract the install/uninstall functionality to a ThemeInstaller

Issue #2271529 by attiks, alexpott, Lowell, YesCT, Jelle_S | mdrummond: Move breakpoint settings to theme and module *.breakpoints.yml files at root level.

Issue #1067408 by alexpott, Jalandhar, jessebeach, Désiré, neetu morwani, dawehner, sun: Themes do not have an installation status.

This reverts commit ae8be3cc.

Issue #2109287 by dawehner, Cottser, tim.plunkett, kim.pepper: Replace list_themes() with a service.