Update to typescript-eslint v8 (#6372)

* Update typescript-eslint to v8

* Disable @typescript-eslint/prefer-optional-chain

This rule now requires type information which is not currently enabled for
the Typescript ESLint checks.

* Remove unused vars

* Disable no-empty-function for line using updated config

* Disable rule for lines that violate updated typescript-eslint rules

* Use void operator to fix no-floating-promises

Co-authored-by: Bill Thornton <thornbill@users.noreply.github.com>

* Use void operator to fix no-floating-promises

Co-authored-by: Bill Thornton <thornbill@users.noreply.github.com>

---------

Co-authored-by: Bill Thornton <thornbill@users.noreply.github.com>

src/components/alphaPicker/AlphaPickerComponent.tsx

@@ -7,7 +7,7 @@ type AlphaPickerProps = {
 };
 
 // React compatibility wrapper component for alphaPicker.js
-// eslint-disable-next-line @typescript-eslint/no-empty-function
+// eslint-disable-next-line no-empty-function
 const AlphaPickerComponent: FunctionComponent<AlphaPickerProps> = ({ onAlphaPicked = () => {} }: AlphaPickerProps) => {
     const [ alphaPicker, setAlphaPicker ] = useState<AlphaPicker>();
     const element = useRef<HTMLDivElement>(null);