Add --music command line input switch to lilypond / lyp compile

[noteflakes]

Add --music/-M (--music-relative/-m for relative mode) switch that allows entering music directly on the command line. Some examples:

# absolute mode
$ lilypond -M "c'4 d' e' f' g'1"
#=> compiles to a PDF with a random name

# -M/--music-relative - means \relative c'
$ lilypond -m "c4 d e f g1"

# produce a PNG snippet
$ lilypond -Sm "c4 d e f g1"

# set output file
$ lilypond -Sm "c4 d e f g1" -o my-snippet