Implement compatibility with Linux VST, MacVST and AAX

[QuetzalcoutlDev]

Enhancement Summary

Compatibility with LinuxVST, MacVST and AAX plugins

Justification

Because Wine is not a totally effective solution for VST compatibility, because in LMMS they don't implement LinuxVST compatibility but still allowing the use of Wine, since there are many plugins that only exist for Windows or Mac, and on MacOS I think it would be good to implement compatibility with MacVST There are also AAX plugins I think that's what they're called, it would be nice if LMMS is also compatible with them I don't know if this is already being implemented or if they have already requested it.

Mockup

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[PhysSong]

AAX plugins are only for Pro Tools, as Avid doesn't provide a SDK to develop AAX hosts. They only provide SDK for plugin development which is not compatible with the GPL2+ license of LMMS.
VSTs on macOS is being tracked by #3975. On Linux, it's implemented by #6048 and available in nightly versions.
As an alternative, VST plugins can be bridged via Carla. See #4558 for macOS.

[QuetzalcoutlDev]

@PhysSong Yes, I found out a while ago that since AAX is only for ProTools, it would also be good to implement VST 3 compatibility in LMMS, is it possible?

[RiedleroD]

#4715