Correctly detect file-local NoUnicodeSyntax

[Aster89]

This change contains:

1. a relatively small edit to take into account possible {-# LANGUAGE UnicodeSyntax #-}/{-# LANGUAGE NoUnicodeSyntax #-} in the file being edited, and to treat those with higher priority than the corresponding flags in (corresponding stanza in) the .cabal file,

2. a test that looks a bit ugly right now;

Regarding 2, my intent is to test for the 9 combinations of {-# LANGUAGE UnicodeSyntax #-}/{-# LANGUAGE NoUnicodeSyntax #-}/neither × corresponding 3 alternatives in the .cabal file, and I've tried, but the code looks messy…

Suggestions?

• I read and followed our AI policy

Fix #5067.

[fendor]

LGTM, one nitpick and a suggestion that I am fine to do in a follow-up

[fendor]

It would have honestly been far easier to write a direct cradle test like this:

cradle:
  direct:
    arguments:
    - Module
    - -XGHC2024

Since you care about the base arguments to GHC, rather than that it is a cabal project.

We can merge as is, create an issue to convert it to a direct cradle test.
Direct cradle tests are much faster since we don't need to load the cabal context.

[Aster89]

Ok, I'll create an issue for that.

To understand a bit more, do you mean that I would write

      $ let cradleFile = [
              "cradle:",
              "  direct:",
              "    arguments:",
              "    - Module",
              "    - -XGHC2024",
              ]

and, similarly to what I've done, I'd add another line to mean "add UnicodeSyntax" / "add NoUnicodeSyntax"?