Allow expressions as arguments to attributes

[casey]

Currently, recipe attributes like [confirm: 'prompt'] only allow string literal arguments. Ideally, these should all be able to take arbitrary expressions, like [confirm: 'are you sure you want to delete ' + path + '?'].

This has been brought up in a number of issues:

https://github.com/casey/just/issues/553 https://github.com/casey/just/issues/1855 https://github.com/casey/just/issues/1996 https://github.com/casey/just/issues/2510 https://github.com/casey/just/issues/2521

[casey]

Looking at the attributes, I think all of them should be able to take expressions as arguments, with the possible exception of [group], which needs to be evaluated without executing anything.

[Beiri22]

That would be really nice. So I could use an auto generated path as working-directory... Is there any news on that?

[ofek]

Would this be too difficult of a task for a first-time contributor?