Enable LV2 plugin support

[SubhadeepJasu]

Enabling LV2 plugin support will allow Ensembles to use multiple good quality lv2 plugins out there like Dexed. But also connect to plugin "adapters" like Carla which in turn supports tons of other plugin types including VST.

[wepache]

This would make this program 10x better.

[wepache]

Also I would assume that since the project can only be downloaded as a flatpak, LV2 plugins will need to be in flatpak for them to work. I feel that the most effective way for this to work is to allow Ensembles to be installed as a deb file on Ubuntu and debian so that we are able to use the KXStudio Repos to get a huge variety of open source LV2 that are not in flatpak.

[SubhadeepJasu]

Update on LV2 support (Only applies to beta development):

• The app can now load multiple LV2 plugins (From LV2 examples and the ones from ZRhythm ZPlugins)
• There's two main categories: DSP (or Effects) and Voice (or Instruments)
• For now DSP plugins appear in the Global DSP Rack. Where dsp effects can be inserted from a list.
• Voice plugins appear in the usual Voice menu at the bottom of the list after the soundfont voices.
• Not all features work, and there's still a lot of crashing issues related to the lv2 host implementation (which I will need to fix)
• The video below shows me playing with ZSaw (an instrument plugin) and ZVerb and ZPhaser (DSP). [The beta UI is not nearly complete].

2023-08-15.18-22-52.mp4

• Below are some screenshots of the plugins, racks, etc:

Tracking in #87