Issue #3281535 by mondrake, daffie: Fix 'Access to an undefined property' PHPStan L0 errors in test code

Issue #3082655 by Wim Leers, alexpott, iyyappan.govind, dww, lauriii: Specify the $defaultTheme property in all functional tests

Issue #1927648 by damiankloip, Wim Leers, marthinal, tedbow, alexpott, Arla, juampynr, garphy, bc, ibustos, eiriksm, larowlan, dawehner, gcardinal, kylebrowning, vivekvpandya, Sam152, neclimdul, pnagornyak, drnikki, queenvictoria, gaurav.goyal, kim.pepper, Berdir, clemens.tolboom, blainelang, moshe weitzman, webchick, linclark, dabito, skyredwang, Dave Reid, gabesullice, dagmar, klausi, andypost, aheimlich, slashrsm, pwolanin, xjm, catch, amateescu: Allow creation of file entities from binary data via REST requests

Issue #2805281 by Wim Leers, damiankloip: ?_format=hal_json error responses are application/json, yet should be application/hal+json

Issue #2737719 by Wim Leers, dawehner: EntityResource: Provide comprehensive test coverage: for every entity type, every format, every method

Revert "Issue #2737719 by Wim Leers, dawehner: EntityResource: Provide comprehensive test coverage: for every entity type, every format, every method"

This reverts commit 59781ffc.

Issue #2737719 by Wim Leers, dawehner: EntityResource: Provide comprehensive test coverage: for every entity type, every format, every method