fix 'unkown command elxir with rtx' and fish

[Whoops]

Currently, when I try to use elixir-ls with fish in vscode it fails to start with the following failure:

Preferred shell is fish, launching launch.fish
Looking for ASDF install
ASDF not found
Looking for rtx executable
rtx executable found in /usr/bin/rtx, activating
fish: Unknown command: elixir
./scripts/launch.fish (line 79): 
echo "" | elixir "$scriptpath/quiet_install.exs" >/dev/null || exit 1

Chasing this down a bit, RTX relies on the fish_prompt and fish_preexec to do its magic, and fish_prompt is never fired in a script, so unless vscode is launched from a shell where RTX has already set its environment variables, activating RTX won't work. Since Elixir-LS doesn't need the directory-changing magic, I think rtx env is the way to go here.

[lukaszsamson]

I don't know nor use fish so I'm pinging other contributors. Can you help with reviewing? @Defman21
@ForLoveOfCats @jaminthorns

[Defman21]

Well, rtx env is the way to use rtx only in current session (without touching user's fish configuration), which I guess is fine for the case of running elixir-ls. As long as it works both from running vscode via the terminal and UI, then LGTM.

I'll test this PR just in case and tell the results shortly.

[Defman21]

Running VSCode from terminal and GUI: both working fine, elixir is found and elixir-ls works! 🎉

macOS Sonoma 14

[jaminthorns]

I've never used rtx, but upon reading through the documentation, rtx env definitely seems like the more appropriate command to use.

Given that, we should probably switch from rtx activate to rtx env in the launch.sh script as well:

elixir-ls/scripts/launch.sh

Line 56 in ccb05ac

eval "$($(which rtx) activate "$preferred_shell")"

@lukaszsamson If you agree, should that be done in this PR or a separate one?

[lukaszsamson]

Thanks all. @jaminthorns good point. I went ahead and did the change in 4894b38