Control view for chain's mixer controls

[riban-bw]

Is your feature request related to a problem? Please describe.
The mixer view offers access to some of the audio mixer's controls, e.g. fader, mute, solo, pan but not all of them and it may be challenging to perform some operations, e.g. binding MIDI CC, fine control, etc.

Describe the solution you'd like
For each chain that fees the audio mixer (audio, synth, etc.) provide control pages so that the control view can be opened and each parameter accessed. This should be at the end of the control pages or maybe at the fader postion, i.e. between pre and post fader processors' control pages.

Describe alternatives you've considered
The mixer has improved touch control and MIDI learning but it may be further enhanced with this request.

Additional context
We may need to present the mixer as a processor or multiple processors.

[riban-bw]

I am working on this and will soon create a dev branch for this development. It allows each mixer strip to be added to the zynmixer engine as a separate processor. These processors appear in the chain so can be moved around like any other processor although I think we should keep them in their own slots, i.e. not have a mixer strip in parallel with any other effect. This simplifies the logical design and implementation. I have split the mixer into two jack clients with the input channels in one and the mixbuses in the other which reduces latency for post-fader effects chains.

[riban-bw]

I have pushed the dev branch to GitHub but it needs more work. It is working as a proof-of-concept but there will be many bugs and issues that need resolving.