IgxGrid: after selecting multiple cells using CNTL / click should be able to deselect an individual cell using CNTL / click

[IGvaleries]

Is your feature request related to a problem? Please describe.

After selecting a bunch of cells in the grid there is no easy way to deselect one cell while leaving the other cells selected

Describe the solution you'd like

After selecting multiple cells using CNTL / click should be able to deselect an individual cell using CNTL / click

[hanastasov]

Currently, there is no way to deselect a cell. With the implementation of this feature, this possibility will be available, so we need to think of UX perspective - do we need to use the old selected event to notify if a cell has been deselected, or expose a new event, that will be emitted on deselection.

1. selected event emits the cell, which has been selected. Same event can be emitted for deselection (maybe a bit strange, not sure). eventArgs.cell.selected will return the correct selected state. No breaking change
2. Emit a new event, for example deselected when a cell is deselected.

@MonikaKirkova, lets go with 1st option now.

@sdimchevski , do you have any preference over the option to go? Please share your thoughts or let us know if you need more time to think about it.

[MonikaKirkova]

I have discussed this with @sdimchevski and according to him we could emit the selected event when deselecting a cell.