* MM-21019 - Fix race in (*Environment).SetPluginState()
- We change from passing pointers to registeredPlugin to passing
the struct by value.
- We also add a mutex to the supervisor struct to protect
from racy data access.
* move the immutability comment to the godoc of the Active method
* Changing mut to lock
Co-authored-by: mattermod <mattermod@users.noreply.github.com>