feat: port to KiCad v8

[kamoteshake]

I ported it to KiCad v8.0.3. I also fixed some errors when updating the PCB from the schematics.

Here are the errors I was getting:

The errors were pretty much because there are a bunch of components (Player 1 and 2 ports and the power/reset board) in the schematic that doesn't need to be in the PCB. Solved it by adding # to all of the references that doesn't have any footprint. I grouped them by using dashed boxes to add some context.

For the warnings, the symbol for X1 (Clock) only have 2 pins while the footprint have a 3rd one. I ended up changing the symbol to Device:Crystal_GND3 and just add a No Connect on the 3rd pin.

And this is the result.

[kamoteshake]

Closing this to not conflict with the upcoming release. Will apply these changes after the release.