Add Soldered PCB version

[hongaaronc]

Pre-Requisites:

These changes are built on top of the changes in #2, so please review that first.

Description:

I didn't originally intend to have a soldered PCB variant for the 065, but it was often requested in the IC feedback. I've made a variant to address that - whether it goes to production in the GB is still TBD, but this should be production-ready in theory nonetheless.

Approach:

Made a copy of the hotswap PCB and worked off that. I managed the preserve the switch matrix, but had to do something a bit janky with the newly added key from split backspace - that key is connected to R2 (next to the enter key matrix-wise) to preserve the matrix.

I'm not sure if I want to keep RGB in this version or not. For now though, I've kept the original RGB LEDs - so the keys from the original fixed hotswap layout will have per-key RGB, but some of the new keys like split backspace and split left-shift will not. Not sure if there's a better way to approach this cleanly.

Components-wise, this is mostly the same as the hotswap PCB, of course without the Kailh hotswap sockets. I did however, have to add a few diodes to support some of the additional keys, namely split spacebar, and split backspace.

Supported Layouts:

Schematic:

PCB: