AFP UI: Hide loopback point and knob when loop mode disabled

[Monospace-V]

Enhancement Summary

When loop mode is set to disabled, hide loopback knob and loopback marker.
Currently our AudioFileProcessor shows loopback point knob and loop marker and highlight even when loop mode is disabled. See:

Implementation Details / Mockup

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[bratpeki]

I've spoken about this on Discord, so I'll be brief.

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There's a reason the "no loop" option is the largest one. That's enough indication to me that we're not looping anything.

It also looks kind of odd with that gaping hole, and the UI nicely uses arrows, so moving them around would look weird (meaning ⬅️, ➡️, ➡️⬅️ would look weird as opposed to ⬅️, ➡️⬅️, ➡️).

Also, we're treating the user like they're incompetent to notice the loop option set on the sample. The more stuff we hide, the less the user looks at it, and the less it sticks in his memory.

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I dunno, I don't want to make too big of a deal of such a small feature, but I don't think this should be made, simply because of the UI and UX issues.

[Monospace-V]

The fact we use the same sort of buttons for loop options (radio toggle) as we do for sample playback mode (checkbox) is also something we might want to change in the future. This is a cause for concern: two similar-looking types of button sets shouldn't behave differently.
Presently, I do think this (showing the knob when loop mode is off) is a non-issue, and am yet to meet a user affected or confused by it.

[Spacemagehq]

I like it but I agree with @bratpeki the gap does look off.

[Monospace-V]

Could we grey it out?
This reminds me of envelopes, where "freq" and "reso" envelope tab settings can be edited even with the filter off. Do we have precedent for this? We have precedent: the decay and gate knobs are greyed out when "Keep effects playing even without input" is enabled.