feat: UI.Table density prop

[mattrunyon]

Fixes #559

Relies on deephaven/web-client-ui#2151 and will need a new version to consume for the types.

You can test this without needing an alpha version because @deephaven/iris-grid is an externalized package. Just run the local UI from the web-client-ui PR with the local plugin server

import deephaven.ui as ui
import deephaven.plot.express as dx

stocks = dx.data.stocks()
t_default = ui.table(stocks)
t_normal = ui.table(stocks, density="normal")
t_compact = ui.table(stocks, density="compact")
t_spacious = ui.table(stocks, density="spacious")