Hook up layer tree structure with frontend (#372)

* Hook up layer tree structure with frontend (decoding and Vue are WIP)

* Fix off by one error

* Avoid leaking memory

* Parse layer structure into list of layers

* Fix thumbnail updates

* Correctly popagate deletions

* Fix selection state in layer tree

* Respect expansion during root serialization

* Allow expanding of subfolders

* Fix arrow direction

Co-authored-by: Dennis Kobert <dennis@kobert.dev>

frontend/src/utilities/input.ts

@@ -126,6 +126,5 @@ export async function onWindowResize() {
 }
 
 export function makeModifiersBitfield(e: MouseEvent | KeyboardEvent): number {
-	// eslint-disable-next-line no-bitwise
 	return Number(e.ctrlKey) | (Number(e.shiftKey) << 1) | (Number(e.altKey) << 2);
 }