A way to specify our own env loading method

[wighawag]

Currently just provide a option to load env var from the .env file

For my use case I need a different mechanism that support "MODE" where it load a multitude of .env. files. This is a relatively common pattern used by vite for example.

For now the only way I could make just work with it was to call just inside just via ldenv which will load these .env files and execute just again

See for example my deploy recipe:

deploy $MODE="local": (compile)
    ldenv just _deploy
_deploy:
    mycommand  --rpc-url $RPC_URL 

This is quite verbose

A solution that could solve this more elegantly could be great, it would also solve : #945

Note that I tried an alternative work around where I set the shell with the following

mode := "local"
export MODE := mode
set shell := ["ldenv", "sh", "-c"]

it worls and I can even set the mode via just --set mode production deploy but this is still verbose and not as clean as just deploy production