ability to format imported files

[bobelev]

==> justfile <==
import 'sub.just'

main_var := 'variable'

@_:
 just --list

@main:
 echo main
 echo {{ main_var }}

==> sub.just <==
@sub:
 echo sub
 echo {{ main_var }}

just --fmt --unstable will format only justfile

just --fmt --unstable -f sub.just raises an error

error: Variable `main_var` not defined
 ——▶ sub.just:4:10
  │
4 │  echo {{ main_var }}
  │          ^^^^^^^^

I see to ways to resolve this:

• --fmt should format imported files automatically
• --fmt can omit undefined variables and just format syntax (doesn't seem right)

[bobelev]

Now we can't even format files with common recipes that don't have variable declaration:

❯ just --fmt -f sub.just  --set main_var "123"
error: `--format` used with unexpected overrides: `main_var=123`