Selection is incorrectly restored in some multi-cell scenarios

[scofalik]

📝 Provide detailed reproduction steps (if any)

Selection fixing, that happens when a selection range goes to the graveyard, works a bit incorrectly at this moment. The algorithm tries to fix every selection range that gets removed. Consider this scenario:

[ ][ ][ ]
[x][x][ ]
[x][x][ ]

This is a 3x3 table, with cells marked with x being selected.

Now, when you remove the second row, you'd expect this result:

[ ][ ][ ]
[x][x][ ]

The second row is removed and the selection stays on those cells that are still in the content. However, the actual result is this:

[ ][ ][x]
[x][x][ ]

Why? Well, two selection ranges were removed and got fixed to select the cell in the upper-right corner.

This happens because the selection post-fixer does not check the selection state. I propose to fix this algorithm. Selection range should be fixed only if it is the last range of the selection. In other cases, we should leave the selection as is.