dcc redesign: refactor `Loading` component #442

Job	Run time
Detect Relevant Path Changes	6s
Build Dash Package	3m 2s
Typing Tests	2m 44s
Table Unit/Lint Tests (Python ${{ matrix.python-version }})	0s
Run Background & Async Callback Tests (Python ${{ matrix.python-version }})	0s
Table Server Tests (Group ${{ matrix.test-group }})	0s
	5m 52s

Provide feedback