feat: add scyjava-stubgen cli command, and `scyjava.types` namespace, which provide type-safe imports with lazy init

[tlambert03]

many more details and tests to follow... but just wanted to open this as a WIP. edit: see https://github.com/scijava/scyjava/pull/82#issuecomment-3207325549 for details

Basic idea, after checking out this branch and running pip install -e . again:

1. create stubs with a cli commend, e.g. scyjava-stubgen org.scijava:parsington:3.1.0
2. Import names provided by that endpoint: python -c "from scyjava.types.org.scijava.parsington import Function; print(Function(1))". Only at the moment of class instantiation will the jvm be started.