Can we improve architecture installation?

[PicoCentauri]

Currently when installing metatrain no architecture(-dependency) is installed. Any architecture has to be installed using the extra syntax like pip install metatrain[pet]. This may be very weird for new users...

Is there is a way to improve this, maybe by installing the dependencies the first time the architecture is called? A quick Google search shows that there are some ways calling pip during runtime but I don't know if this is too hacky for us. But if we find a way this would improve usability a lot.

[Luthaf]

An other thing we could do that would help a bit would be to provide a all extra, that would be used as pip install metatrain[all] (could also be named stable once we get there).

pip install at runtime might be a bit problematic, unless we do this inside a virtualenv, like tox. I would prefer not to modify the user's installation without an explicit prompt.

[PicoCentauri]

I am also not feeling super well do alter the users installation at runtime and all option might be useful and once we have spherical expansion codes on pypi it should also be fast to install.

[PicoCentauri]

Together with @abmazitov, @frostedoyster we decided to improve the error message for now when importing the architecture stating something like:

f"Dependencies for the architecture {architecture_name} not found."
f"Please install them using `pip install .[{architecture_name}] and try again."