Issue #1906810 by dawehner, damiankloip, tstoeckler, kgoel, fubhy, jrglasgow, xjm, Gaelan, socketwench: Require type hints for automatic entity upcasting.

Revert "Issue #1906810 by dawehner, damiankloip, tstoeckler, kgoel, fubhy, jrglasgow, xjm, Gaelan, socketwench: Require type hints for automatic entity upcasting."

This reverts commit c9e73f7d.

Issue #1906810 by dawehner, damiankloip, tstoeckler, kgoel, fubhy, jrglasgow, xjm, Gaelan, socketwench: Require type hints for automatic entity upcasting.

Issue #2246665 by jaredsmith, martin107, YesCT, filijonka, tstoeckler: Typehint with Drupal\Core\Language\LanguageInterface instead Drupal\Core\Language\Language.

Issue #2079797 by ParisLiakos, Xano, amateescu, tim.plunkett: Provide a trait for $this->t() and $this->formatPlural().

Issue #2158571 by tstoeckler, dawehner, kgoel, tim.plunkett, catch, effulgentsia: Routes added in RouteSubscribers cannot be altered.

Issue #2167039 by likin, dawehner, Wim Leers, tstoeckler, vijaycs85: Regression: page cache tags broken, also: some routes incorrectly use _controller -> No page object in template variables -> Fatal in seven_preprocess_page().

Issue #1952394 by vijaycs85, tstoeckler, webflo, Gábor Hojtsy, Schnitzel, falcon03, YesCT, kfritsche, Ryan Weal, dagmita, likin, toddtomlinson, nonsie, Kristen Pol, dawehner, tim.plunkett, penyaskito, EclipseGC, larowlan, robertdbailey, helenkim, David Hernández, EllaTheHarpy, lazysoundsystem, juanolalla, R.Hendel, Kartagis: Add configuration translation user interface module.