add new layout for Ergodox EZ and fix ASCII art for Emojis

[wiserfirst]

• At the moment, the layout_editor/default.json for Ergodox Ez references an incorrect index for the bottom right key on the left half of the keyboard. The correct index should be 72, but it uses 37, which is actually for the L key on QWERTY layout.
• Add a plain layout for Ergodox, which handles the keymap layout created with LAYOUT_ergodox
• Another issue is that if the legend contain emojis, string.format can not align the ASCII art properly, so created a custom_format function to deal with that