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/ServerOfflineDialog.tsx

@@ -33,15 +33,15 @@ import { IDialogProps } from "./IDialogProps";
 interface IProps extends IDialogProps {}
 
 export default class ServerOfflineDialog extends React.PureComponent<IProps> {
-    public componentDidMount() {
+    public componentDidMount(): void {
         EchoStore.instance.on(UPDATE_EVENT, this.onEchosUpdated);
     }
 
-    public componentWillUnmount() {
+    public componentWillUnmount(): void {
         EchoStore.instance.off(UPDATE_EVENT, this.onEchosUpdated);
     }
 
-    private onEchosUpdated = () => {
+    private onEchosUpdated = (): void => {
         this.forceUpdate(); // no state to worry about
     };
 
@@ -87,7 +87,7 @@ export default class ServerOfflineDialog extends React.PureComponent<IProps> {
         });
     }
 
-    public render() {
+    public render(): JSX.Element {
         let timeline = this.renderTimeline().filter((c) => !!c); // remove nulls for next check
         if (timeline.length === 0) {
             timeline = [<div key={1}>{_t("You're all caught up.")}</div>];