Fix #2924. Use MegaParsec scanner for Markdown files

[jonaprieto]

This PR addresses a bug/missing case present since v0.6.2, introduced specifically by

• PR Parallel pipeline #2779,

That PR involves detecting imports in Juvix files before type checking, and that's the issue.
Detecting/scanning imports is done by running a flat parser (which ignores the Juvix Markdown structure) and when it fails, it runs a Megaparser parse. So, for simplicity,
we could just continue using the same Megaparser as before for Juvix Markdown files.

[janmasrovira]

I suggest adding a comment to clarify

[jonaprieto]

@janmasrovira Could you please make Ormolu happy here.
My local version generates a vast delta. 😅

[janmasrovira]

@janmasrovira Could you please make Ormolu happy here. My local version generates a vast delta. 😅

Done! If you want you can install the same ormolu version that we use in CI with stack install ormolu --resolver=lts-21.25.

[jonaprieto]

I tried:

stack install ormolu --resolver=lts-21.25
[1 of 3] Compiling Main             ( /Users/jonaprieto/.stack/setup-exe-src/setup-HwdwpEmb.hs, /Users/jonaprieto/.stack/setup-exe-src/setup-HwdwpEmb.o )
[2 of 3] Compiling StackSetupShim   ( /Users/jonaprieto/.stack/setup-exe-src/setup-shim-HwdwpEmb.hs, /Users/jonaprieto/.stack/setup-exe-src/setup-shim-HwdwpEmb.o )
[3 of 3] Linking /Users/jonaprieto/.stack/setup-exe-cache/aarch64-osx/tmp-Cabal-simple_HwdwpEmb_3.8.1.0_ghc-9.4.8
ld: unknown options: --gc-sections
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ghc-9.4.8: `gcc' failed in phase `Linker'. (Exit code: 1)

Error: [S-6374]
       While building simple Setup.hs (scroll up to its section to see the error) using:
       /Users/jonaprieto/.stack/programs/aarch64-osx/ghc-9.4.8/bin/ghc-9.4.8 -rtsopts -threaded -clear-package-db -global-package-db -hide-all-packages -package base -main-is StackSetupShim.mainOverride -package Cabal-3.8.1.0 /Users/jonaprieto/.stack/setup-exe-src/setup-HwdwpEmb.hs /Users/jonaprieto/.stack/setup-exe-src/setup-shim-HwdwpEmb.hs -o /Users/jonaprieto/.stack/setup-exe-cache/aarch64-osx/tmp-Cabal-simple_HwdwpEmb_3.8.1.0_ghc-9.4.8
       Process exited with code: ExitFailure 1

It's probably due to my mac.