Add Spacebar support (back?) for the new client rewrite.

[AeonRemnant]

I had a poke around and it seems this was removed a while ago for the reasoning that it was too different? But given that Discord is going the enshittification way ever since the CEO switch and IPO, it makes sense to add third party Discord servers as actually supported in Webcord since the rest of the wider solutions like Revolt are woefully incomplete.

Naturally this would go hand in hand with the new client rewrite.