Record beat and baseline using midi controllers

- [x] *Please search the issue tracker for existing feature requests before submitting your own. Delete this line to confirm no similar request has been posted yet.*

### Enhancement Summary

There are a bunch of midi pads that support input as midi controllers instead of traditional usage over sound fonts.

A sound font has a few aspects that make it unusable in some cases.

#### Bad Aspects of sound fonts

- Hard to setup
- Working with beat midi tracks is confusing and hard over software (Caused by the additional features like note length which you don't need when working with beats)
- Can't add Effects on the single instruments
- Can't control the volume on the single instruments
- Can't separate the instruments which makes some effects like side chain compression unusable

#### Idea

Add a way to record a beat and baseline using midi controller, that are attached to an individual instrument.

---

### Justification

#### Attaching

In the beat and baseline tab you could attach a controller to an instrument which you have added before (for example the snare drum).

#### Playing

When we now activate the specific midi controller it plays a note from the instrument we bound the controller too. This works with multiple instruments at the same time.

#### Record button

There will be a new record button which allows us to record beat and baselines using our previously attached midi controllers.

---

### Mockup

As stated before, we would have to add a record button to the beat and baseline tab. It would look somewhat like the record button in the Piano-Roll window.


We would also need to add a window to attach a controller to an instrument. This window will be available by clicking on the Settings icon and selecting 'Attach to controller'. The window itself would look somewhat like the 'Connect to controller' window for connecting controllers to sliders and knobs.


No files, tests, or entry points are named. Start by surveying the beat and baseline tabs, the Piano-Roll record control, and the existing controller-connection window; the proposed work is only complete when controllers can be attached to individual instruments, trigger them, and record beats and basslines.

Written by the indexing model from the issue text.