feat: add more keycodes

[ahaoboy]

Add support for the four function keys in the 108-key Windows keyboard layout

Reference: https://learn.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes

Also add support for a trailing comma in the decl_keycodes macro.

[ahaoboy]

Should we directly convert all legal key names in this document into Rust enum?