Refactor cells

[seefeldb]

First step of refactoring: Teaching RendererCell about schemas, etc. (this will eventually become the cell).

[anotherjesse]

There doesn't appear to be any breakage - except for tests

main...refactor-cells-merge is my fix of the merge conflict

it breaks two tests - where it expects "item" instead of "element" in the alias for x:

 ❯ test/recipe.test.ts:226:7
    224|     expect(
    225|       (multiplyArray.nodes[0].inputs as { op: Recipe }).op.nodes[0].inputs,
    226|     ).toEqual({
       |       ^
    227|       x: { $alias: { cell: 1, path: ["argument", "item", "x"] } },
    228|       factor: { $alias: { path: ["argument", "factor"] } },