`Grid` component: Expressions to hide entire rows/columns/cells

### Description

In #107, it's mentioned that it should be possible to hide rows/cells/columns in table components. This seems most applicable and useful to the `Grid` component. That mention has been extracted to this issue.

It should be possble to put these expressions on both a row and cell configuration, possibly also with an expression on the cell-level on the first cell in the table where it is possible to hide an entire column.

Make sure that:
- Hiding a row/column/cell also hides the component(s) within them. Expressions looking up the `["component", ...]` value for a hidden component should return `null` even if the component has data in the data model.
- If `colSpan` and `rowSpan` has been implemented, hidden rows/columns hide the rows/columns they span over, and possibly inversely, are spanned by. This could get complicated, so take shortcuts where needed - but document them.

### Additional Information

- #107
- #583
- #1187

Start by reading issues #107, #583, and #1187, then locate the Grid row and cell configuration entry points. Define how expressions hide rows, columns, and cells, including component lookup results and the documented behavior for rowSpan and colSpan; completion should cover these cases in the Grid component.

Written by the indexing model from the issue text.