Refactor (#862)

* Initial factoring out of parts of the LayerUI component

2360 → 2224 LOC

* Create a Section component

* Break up src/index.tsx

* Refactor actions to reduce duplication, fix CSS

Also consolidate icons

* Move scene/data.ts to its own directory

* Fix accidental reverts, banish further single-character variables

* ACTIVE_ELEM_COLOR → ACTIVE_ELEMENT_COLOR

* Further refactoring the icons file

* Log all errors

* Pointer Event polyfill to make the tests work

* add test hooks & fix tests

Co-authored-by: dwelle <luzar.david@gmail.com>

src/tests/queries/toolQueries.ts

@@ -14,9 +14,9 @@ const _getAllByToolName = (container: HTMLElement, tool: string) => {
   return queries.getAllByTitle(container, toolTitle);
 };
 
-const getMultipleError = (c: any, tool: any) =>
+const getMultipleError = (_container: any, tool: any) =>
   `Found multiple elements with tool name: ${tool}`;
-const getMissingError = (c: any, tool: any) =>
+const getMissingError = (_container: any, tool: any) =>
   `Unable to find an element with tool name: ${tool}`;
 
 export const [