Add OSC input to request avatar config reload

[bdunderscore]

What's the idea?*
Provide a well-defined OSC endpoint that requests that VRChat reload (and/or regenerate) the avatar OSC configuration.

Is there another way?
The user could change avatars and back, but this is inconvenient.

Additional context
This allows external tools to automatically reconfigure the OSC configuration as needed without unnecessary user intervention. It might be particularly useful in combination with #2.

[momo-the-monster]

Might roll up well with #5 and #11 as well

[theolliedev]

@momo-the-monster Hi there, I would love to see this feature to be implemented, do we have news on this?
Thanks!