Falke Carlsen keymap for GMMK PRO ISO

Based on the default keymap, inheriting rotary encoder and LED configs without modification.

Changes:

Fixes layer 1 of top-row to correspond to 'Keychron ISO Q1 & K2 Dye-Sub PBT Nordic' printed legend multimedia keys.
Adds early 2010s Ducky layer 1 mouse-emulation to WASD with left+right click and scroll in the 2x4 cluster.
Remaps default keymaps LED-handling to 2nd-row due to addition of mouse-emulation.
Swap layer 0 rotary encoder click to play/pause, and layer 1 click to next.