use the `run` command of `conda` / `mamba` / `micromamba`

[keewis]

jupyter-forward currently creates a script with two steps:

1. activate environment
2. launch jupyter lab

Which is designed to be executed remotely.

This adds a lot of complexity, which may be avoided by using the run command of recent versions of conda / mamba / micromamba, but without requiring the presence of a shell hook. conda has supported this since 4.12.x (released Mar 8, 2022), micromamba since 2022.02.07, and for mamba this is not quite clear, but the earliest version compatible with python=3.9 is mamba=0.5 (released in 2020), which supports it.

Additionally, it would allow supporting pixi / uv, we'd just have to make sure to set $PWD appropriately before using those (that's my main intention for opening this issue, but it may also resolve #248).

Finally, we could allow specifying the environment manager in an additional option (either as a absolute path or a command to be resolved using $PATH).

[andersy005]

This adds a lot of complexity, which may be avoided by using the run command of recent versions of conda / mamba / micromamba, but without requiring the presence of a shell hook. conda has supported this since 4.12.x (released Mar 8, 2022), micromamba since 2022.02.07,

i wasn't aware of this.. this is a nice feature

i'm in favor of this addition. a PR is very welcome