improve configuration comfort in keyboard.toml

[tib888]

• morses should have an optional name attrib, so TD(name) could be used instead of TD(#)
• morse, combo, fork configs should be able to resolve layer/morse names, aliases
• (allow recursive aliases?)

for example instead of:

[behavior.combo]
combos = [
   { actions = ["Esc", "Backspace"], output = "TG(4)" }, #toggle nav layer
]

this could be written:

[behavior.combo]
combos = [
   { actions = ["Esc", "Backspace"], output = "TG(nav)" },
]