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/structures/auth/header/AuthHeaderDisplay.tsx

@@ -24,7 +24,7 @@ interface Props {
     serverPicker: ReactNode;
 }
 
-export function AuthHeaderDisplay({ title, icon, serverPicker, children }: PropsWithChildren<Props>) {
+export function AuthHeaderDisplay({ title, icon, serverPicker, children }: PropsWithChildren<Props>): JSX.Element {
     const context = useContext(AuthHeaderContext);
     if (!context) {
         return null;

src/components/structures/auth/header/AuthHeaderModifier.tsx

@@ -25,7 +25,7 @@ interface Props {
     hideServerPicker?: boolean;
 }
 
-export function AuthHeaderModifier(props: Props) {
+export function AuthHeaderModifier(props: Props): null {
     const context = useContext(AuthHeaderContext);
     const dispatch = context ? context.dispatch : null;
     useEffect(() => {

src/components/structures/auth/header/AuthHeaderProvider.tsx

@@ -32,7 +32,7 @@ interface AuthHeaderAction {
 
 export type AuthHeaderReducer = Reducer<ComponentProps<typeof AuthHeaderModifier>[], AuthHeaderAction>;
 
-export function AuthHeaderProvider({ children }: PropsWithChildren<{}>) {
+export function AuthHeaderProvider({ children }: PropsWithChildren<{}>): JSX.Element {
     const [state, dispatch] = useReducer<AuthHeaderReducer>(
         (state: ComponentProps<typeof AuthHeaderModifier>[], action: AuthHeaderAction) => {
             switch (action.type) {