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/UserSettingsDialog.tsx

@@ -80,7 +80,7 @@ export default class UserSettingsDialog extends React.Component<IProps, IState>
         this.setState({ newSessionManagerEnabled: newValue });
     };
 
-    private getTabs() {
+    private getTabs(): Tab[] {
         const tabs: Tab[] = [];
 
         tabs.push(
@@ -210,7 +210,7 @@ export default class UserSettingsDialog extends React.Component<IProps, IState>
         return tabs;
     }
 
-    public render() {
+    public render(): JSX.Element {
         return (
             <BaseDialog
                 className="mx_UserSettingsDialog"