Improve ValueList customizability

[grliszas14]

Resolves: audacity/audacity#9841

List of changes:

• added vertical line dividing keys and values (both for MS4 and AU4)
• made sorting by key/value customizable
• added a function handler allowing to dynamically decide if given key can be editable or not
• changed navigation for tables that allow keys editing

• I signed the CLA
• The title of the PR describes the problem it addresses
• Each commit's message describes its purpose and effects, and references the issue it resolves
• If changes are extensive, there is a sequence of easily reviewable commits
• The code in the PR follows the coding rules
• There are no unnecessary changes
• The code compiles and runs on my machine, preferably after each commit individually
• I created a unit test or vtest to verify the changes I made (if applicable)

QA:

• please test these preferences: Advanced, Shortcuts, MIDI mapping. The only change should be new vertical line in the middle of the tables

[Eism]

There will be a warning here - isReadOnlyFunction may be null

[DmitryArefiev]

Tested on Win10. No regressions found.

• please test these preferences: Advanced, Shortcuts, MIDI mapping. The only change should be new vertical line in the middle of the tables

@bkunda @avvvvve @jessjwilliamson Please check/approve this vertical line

bandicam.2025-11-17.01-16-21-163.mp4

[Tantacrul]

Perfect. Approved. @DmitryArefiev