Add ChameleonPluginBootstrap to allow users to provide custom plugin creation logic

[joshuasing]

Confirmation

• I have checked for similar issues.

Problem

Chameleon currently creates a new instance of the ChameleonPlugin class via reflection.
This does not allow for any custom creation logic, and could cause instantiation issues to go undetected until runtime.

Suggested solution

We could add a ChameleonPluginBootstrap interface that could be used instead of providing a ChameleonPlugin class.
Paper provides a similar functionality: https://docs.papermc.io/paper/dev/getting-started/paper-plugins#bootstrapper

Additional information

No response