Enable the prefer-destructuring eslint rule (#1858)

## Description:

Enable the `prefer-destructuring` eslint rule.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

src/core/game/UnitGrid.ts

@@ -94,7 +94,7 @@ export class UnitGrid {
   private getCellsInRange(tile: TileRef, range: number) {
     const x = this.gm.x(tile);
     const y = this.gm.y(tile);
-    const cellSize = this.cellSize;
+    const { cellSize } = this;
     const [gridX, gridY] = this.getGridCoords(x, y);
     const startGridX = Math.max(
       0,