feat(Note): Store TransposedPitch (for API access)

when a note is transposed, its .Pitch is still the untransposed one.
Calculating the transposed pitch is quite difficult for developers,
so this is helpful information.

discussed on Discord

src/MusicalScore/Graphical/MusicSheetCalculator.ts

@@ -2491,6 +2491,7 @@ export abstract class MusicSheetCalculator {
             pitch = graphicalNote.Transpose(
                 accidentalCalculator.ActiveKeyInstruction, activeClef, transposeHalftones, octaveEnum
             );
+            graphicalNote.sourceNote.TransposedPitch = pitch;
         }
         graphicalNote.sourceNote.halfTone = pitch.getHalfTone();
         accidentalCalculator.checkAccidental(graphicalNote, pitch);

src/MusicalScore/VoiceData/Note.ts

@@ -57,6 +57,8 @@ export class Note {
      * The untransposed (!!!) source data.
      */
     private pitch: Pitch;
+    /** The transposed pitch, if the score is transposed, otherwise undefined. */
+    public TransposedPitch: Pitch;
     public displayStepUnpitched: NoteEnum;
     public displayOctaveUnpitched: number;
     public get NoteAsString(): string {