feat(app): Stub out flex stacker in deck config

[smb2268]

Fix EXEC-1087 EXEC-1109

Overview

This PR adds interim support for the stacker and stacker+waste chute in deck config. In later iterations, these will be separated out into a new 4th column instead of also taking up column 3

Test Plan and Hands on Testing

Select D3 on deck configuration for a device with unconfigured stacker, see that you're able to add stacker with or without waste chute
Select A3-C3 and see you're only able to add the stacker

Changelog

1. Add necessary types for flex stacker fixtures with and without waste chute
2. Update DeckConfigurator to display flex stacker items
3. Update AddFixtureModal to display flex stacker for all 3rd column slots, flex stacker and waste chute options for D3

Review requests

Test this out on a bot with an unconfigured stacker

Risk assessment

Low

[vegano1]

fantastic!
I tested it and it works as expected, thank you!