Add options to Python language module

[totoroot]

Recently I continued using devenv for various different projects at work, so the need to have it also manage multi-language development environments got bigger.

For a lot of projects, the structure looks similar to the following.

project
├── backend
├── devenv.lock
├── devenv.nix
├── devenv.yaml
└── frontend

In this example backend would for example be the subdirectory of some Python/Django component and then there would be the frontend subdirectory e.g. some JavaScript/Node.js component.

For that reason I would like to specify a subdirectory for the individual components.

In this PR I made the necessary changes to be able to specify a working directory via languages.python.directory.
While it is already possible to pass paths of requirements files to install dependencies from, it is currently not possible to specify the location of the virtual environment or to change the working directory of the poetry command.

This makes it impossible to have the pyproject.toml file anywhere other than at the devenv root.

I also added some more missing options to languages.python.poetry.install.

[totoroot]

I'm planning on adding support for pdm soon, and for that, these changes would facilitate its use as well.

Also, I don't think we don't want to use lib.types.path for the directory, as that would mean copying the subdirectory's content to the Nix store. Using lib.types.str and the root of the top-level devenv project as default seems fine, but please let me know in case you think otherwise.

[totoroot]

If nothing speaks against it, I would go ahead and try adding a similar option for the JavaScript module, since one might also want to have the package.json in a different directory than the devenv root

[domenkozar]

See also #899, I'd really like to have a test for this before it's merged.

[totoroot]

@domenkozar I have modified the example for python-poetry to include the newly added options.

I also added an example and tests for the introduced directory option, as you requested. In this example I have also tested the python-poetry module with the Python directory option set.

[domenkozar]

does it work if you do ./. with types.path and then do config.devenv.root + cfg.directory?

[totoroot]

I don't think I understand what you mean.

In #993 (comment) I mentioned that using types.str means not copying the specified directory to the Nix store, so poetry is still able to write the lock file.

It also gives users more flexibility when setting the option as they can set it to either an absolute path or a path relative to the devenv root with something like ./directory. I've added an example to the option.

[domenkozar]

I think you should be still able to use types.path to validate it's a path and then do mystringpath + cfg.directory

[domenkozar]

Great work, only two comments and it's ready to go :)

[domenkozar]

@totoroot ping :)

[domenkozar]

Can you rebase on main and I'll take over this one :)

[totoroot]

Can you rebase on main and I'll take over this one :)

@domenkozar Sorry, I did not have time to finish this up. Had a lot to do at work since last week, so I'm happy to hand it over to you :)
I have rebased onto main as requested. I hope that all conflicts were properly resolved.