Should we change how we register tasks?

[xhluca]

Right now, registration happens when a benchmark module is imported, e.g. import browsergym.webarena. As it currently stands, it creates challenges for developers to create a modified version of webarena, since it would be registered twice. This means one would need to copy the entire directory of browsergym/webarena in order to avoid importing __init__.py, even though most of the functions are not modified.

Moving registration from __init__.py to register.py, which is not improted by default, would make life a lot easier.

Thoughts?