Written/sounding pitch switch, part 2

[avvvvve]

Continued from @rpatters1's PR #24784 which resolved #15594

Functional changes to make

@rpatters1, if you want you can start working on this piece while we finalize the UI approach.

When set to "sounding pitch", using the computer keyboard letters for note entry should also input pitches as they sound, not as they are written.

For example, if it's set to sounding pitch and I'm writing for Bb Clarinet, typing C should input a D.

UI changes to make

NOTE: Design for this section is in progress

We're going to move this feature out of the playback bar and make it a preference in the 'Note input' section.

We'll provide at least one of the following additional ways to access it:

• Placement 1: In the piano keyboard context menu
• Placement 2: As a sub-option of "Concert pitch" in the bottom bar
  • This might be solved by changing the checkbox to a button triggering a popup containing both...
    • the (existing) option to display the score in concert pitch (which is linked to an option in Style > Score) and
    • this new feature

While we're looking at the playback bar context menu, we may make "Enable MIDI input" an option available in the 'Audio & MIDI' section of Preferences.

Existing implementation (to be changed)