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/BugReportDialog.tsx

@@ -79,7 +79,7 @@ export default class BugReportDialog extends React.Component<IProps, IState> {
         });
     }
 
-    public componentWillUnmount() {
+    public componentWillUnmount(): void {
         this.unmounted = true;
     }
 
@@ -180,7 +180,7 @@ export default class BugReportDialog extends React.Component<IProps, IState> {
         this.setState({ downloadProgress });
     };
 
-    public render() {
+    public render(): JSX.Element {
         let error = null;
         if (this.state.err) {
             error = <div className="error">{this.state.err}</div>;