Choice Set Manager uniqueness doesn't take into account loaded cells

[renonick87]

Bug Report

In the choice set manager, cells that are already loaded on the module need to be taken into account for uniqueness. Currently, it does not, which can lead to clashes when trying to present new cells.

Reproduction Steps

1. Using a sub-7.1.0 module
2. Load a cell on the head unit
3. Attempt to load a unique cell with identical primary text

Expected Behavior

The new cell has a unique identifier appended to it.

Observed Behavior

The cell fails to load.

[jordynmackool]

Closed by #477.