Move fret diagram specific properties to fret-diagram-details

Move fret diagram specific properties to fret-diagram-details

Wholesale rewrite of input/regression/fret-diagrams.ly to
match new syntax.

Update fret-boards interface in scm/define-grob-interfaces.scm

Define fret-diagram-details property in scm/define-grob-properties.scm

Fix FretBoard definition in scm/define-grobs.scm

Reformat scm/fret-diagrams.scm and add fret-diagram-details.
Also, added fret-diagram orientation property.