Position the table context relative to the first section node

This avoids the column context appearing above caption nodes.

Bug: 72829
Change-Id: I3d790d716e41f5dc2a36cd02540ddadb1083f6a8
TableContext: Simplify row/column overlays styles

Use the same technique for rowContext as for colContext.

Change-Id: Ie00a7d0cd92fe6f1580e9edbc8536fc890c76a7a
Merge "Position the table context relative to the first section node"
Merge "TableContext: Simplify row/column overlays styles"