Enable @typescript-eslint/explicit-function-return-type in /src (#9788)

* Enable `@typescript-eslint/explicit-member-accessibility` on /src

* Prettier

* Enable `@typescript-eslint/explicit-function-return-type` in /src

* Fix types

* tsc strict fixes

* Delint

* Fix test

* Fix bad merge

src/components/views/rooms/wysiwyg_composer/hooks/useWysiwygEditActionHandler.ts

@@ -31,7 +31,7 @@ export function useWysiwygEditActionHandler(
     disabled: boolean,
     composerElement: RefObject<HTMLElement>,
     composerFunctions: ComposerFunctions,
-) {
+): void {
     const roomContext = useRoomContext();
     const composerContext = useComposerContext();
     const timeoutId = useRef<number | null>(null);