Add table view

[jrmoulton]

draft because this is somewhat fragile.

position in the virtualized table is handled internally by the table by manually setting a padding_top. So if the caller of a table ever manually sets a padding top, it will break the table. I did this because using a before_node like how the virtual list does breaks the grid layout.

I've also had to hard code in the column headers by painting them in a position that is different from the layout. In order to get this to work without flashing the column headers I had to add a margin top internally to the table.

These hacks wouldn't be necessary if we had layout support in taffy for subgrids and for position: sticky.

[jrmoulton]

I think I want to rework this so that the table doesn't use taffy for layout