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/dialogs/EndPollDialog.tsx

@@ -35,7 +35,7 @@ interface IProps extends IDialogProps {
 }
 
 export default class EndPollDialog extends React.Component<IProps> {
-    private onFinished = (endPoll: boolean) => {
+    private onFinished = (endPoll: boolean): void => {
         const topAnswer = findTopAnswer(this.props.event, this.props.matrixClient, this.props.getRelationsForEvent);
 
         const message =
@@ -59,7 +59,7 @@ export default class EndPollDialog extends React.Component<IProps> {
         this.props.onFinished(endPoll);
     };
 
-    public render() {
+    public render(): JSX.Element {
         return (
             <QuestionDialog
                 title={_t("End Poll")}