LFO2 sync draft

[nikodemus]

As per #813

TODO:

• Figure out if LFO2 needs a resync like LFO1: right now the assumption is that since it retriggers with note-on, it's "good enough" without a resync. No idea if that's true. --> Decided that it's good enough for now at least: a drone with sync'ed LFO2 might experience some drift over time, though.
• Figure out if LFO1 and LFO2 should set initial phase the same way. Currently LFO1 has more logic about this. Applying that would change LFO2 behaviour, but maybe doing it when sync'ed would be ok? --> Retain old behaviour for unsynced LFO2, match LFO1 behaviour when synced.
• Cleanup: do we need resyncing setters for LFO2? (Do we actually need them for LFO1, could we just wait for the next natural resync?) --> Don't need them for LFO2, but should figure out a nicer way to handle them for LFO1.*
• Implement initial phase behaviour matching LFO1 when synced.
• Documentation.
• Cleanup: we should be able to merge lfo::local::* and lfo::global::* classes.
• Cleanup: nicer way to handle resyncing setters for LFO1. Do we need them, or could we wait for the next clock-driven resync instead? --> Clock based resync is still an option, but now there are less redundant calls.
• Naming: localLFOConfig.waveType is a bit unwieldy. lfo1Config.waveType, etc, maybe? --> lfoConfig[] array, as part of the Rate/Sync/Type menu class unification.
• Cleanup: should be able to merge logic for phase increment computation.
• Cleanup / optimization: cache phase increment, instead of recomputing it every time. --> Nope, decided this is out of scope: there's more than a couple of cases when the cache would need to be invalidated, so if this is done it's better done separately.
• Missing sync menu for LFO2.
• More testing.

[github-actions]

Test Results

28 tests   - 1   28 ✅  - 1   0s ⏱️ ±0s
 5 suites ±0    0 💤 ±0 
 5 files   ±0    0 ❌ ±0 

Results for commit c549b42. ± Comparison against base commit 3696aa0.

This pull request removes 5 and adds 4 tests. Note that renamed tests count towards both.

LFOTest ‑ renderGlobalSine
LFOTest ‑ renderGlobalTriangle
LFOTest ‑ renderLocalSine
LFOTest ‑ renderLocalTriangle
LFOTest ‑ renderSampleAndHold

LFOTest ‑ renderSyncedSine
LFOTest ‑ renderSyncedTriangle
LFOTest ‑ renderUnsyncedSine
LFOTest ‑ renderUnsyncedTriangle_noSync

♻️ This comment has been updated with latest results.

[nikodemus]

#2004 and #2005 supersede this.