dotenv as recipe attribute

[igortg]

First and foremost, thanks for this great tool.

It would be nice to have dotenv as recipe attributes for projects with multiple environments. Having to call with --dotenv-filename (and remember the correct dotenv) is cumbersome.

[dotenv-path: ".staging.env"]
run:
  cargo run .

Seems related to #3069.

[casey]

This seems pretty reasonable. My only hesitation is whether it should be [dotenv], [dotenv-path], or [dotenv-file]. Also, should it imply dotenv-required?

[igortg]

I'd like to set different env files for different recipes, so using just dotenv would be a limitation:

[dotenv-path: ".staging.env"]
recipe1:
    ...

[dotenv-path: ".prod.env"]
recipe2:
    ...

About dotenv-path or dotenv-file - I'd say dotenv-path is more flexible and users can just use dotenv-path: "./.env" to have similar behavior of dotenv-file. But that's a weak guess, dotenv-file would also be ok.

The dotenv-required is trickier. I'd like a "fail early" approach since we are explicitly defining a .env, so IMHO it should be implied. I can't think of a use case where it would be good to have it as "not required"