Add costar stabilizer support

[robotmaxtron]

This case could easily support costar stabilizers but hasn't been implemented yet.

[yangbo]

Can the 1.5u keycaps add costar stabilizers? It's great if the improvement is implemented, I can help but don't know how to start, any ideas?

[robotmaxtron]

No, nor are they needed. This case however could easily support costar stabs for the 2u keys.