✨ MixerParamsEvent channel_data "type" field or similar

### Describe the feature

From my observations, the MixerParamsEvent.channel_data property stores a type field. This is the scope of the of parameter target, where 0 is a channel param, 1 is a mixer param, and 2 is a global project param. I've only worked with encoding them, so the function to encode is as follows (you'll have to adapt it for decoding):
```
(((insertId & 0x7f) << 6) | (slotId & 0x3f) | (type << 13))
```
I used this for my OnlineSequencer.net to FLP converter, which I can provide if you want it (it also has encoders for several plugins, but it's written in JS as to integrate as a userscript).

### What version of PyFLP are you using?

Latest source (v2.2.1+)

### Screenshots, Additional info

_No response_

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