fix #25341: distances from barline & time signature to first note with accidentals

This fixes both http://musescore.org/en/node/25341 and http://musescore.org/en/node/25342, as they share code.

For 25341, the leftmost notehead now clears the left barline by barNoteDistance even if the chord has an accidental that "overlaps" the leftmost note.

For 25342, the distance from time signature to first note is left alone by default, unbess there is an accidental on that note.  if there is, then the distance is reduced by the same amount it would have been reduced by had this been a barline instead of a time signature.