Add predraw API for flawless async layout

[texodus]

This PR adds a new API, predraw(width: number, height: number, options?: PredrawOptions): Promise<() => void>, which allows embedding applications to separately stage the async and sync parts of regular-table rendering, such that multiple async drawing elements can be coordinated to prevent screen jitter.

const commit = await table.predraw(table.clientWidth, table.clientHeight);
requestAnimationFrame(() => commit());