Separate UI state from config

[j5v]

Problem

config should contain only configuration state. It currently contains: configuration state, current project data (tunings and their notes), UI state (selections).

Approach

This is a 'could-do' issue that helps code comply with the principle of separating concerns. It carries regression risk if implemented wholly. It can be ignored for the time being, but the problem might become significant when we provide explicit interfaces for configuration options.

While it's beneficial to save UI state that the user is invested in, it should really be separated out into UI state, and perhaps persisted as a UI state object, so that invested selections are restored over sessions.

Some UI state, like tunings[].notes[].selected would need to be separated out, and use serializable references. Most of the code addresses tunings and notes by .id, but look out for synchronization issues when arrays of objects are mutated.

[j5v]

Gut instinct is to leave this alone until a feature needs the states to be separated.