[Grid Generator] Add Ctrl+click form pull-down lists to allow multiple selection + delete token

[rafstahelin]

When selecting multiple items, such as Loras or samplers, the current process of individually selecting each item, adding a comma, and repeating can be time-consuming, especially when choosing 10 or 20 items.

I propose implementing a system that allows for multi-selection of items using the standard Ctrl key functionality. This would enable users to select multiple items simultaneously, significantly improving efficiency and reducing the time required for the selection process.

Plus, in the same vein, clicking on a listing will remove the token parameter (like lora or sampler, etc). Same behavior as in the status bar of generate where lora's and presets are stacked, with the token method of adding from options menu and removing with cross