Improve performance by selectively importing parts of the stdlib

[paulcadman]

This PR:

• Updates the stdlib dependency to a stdlib ref that uses V2 Package (this can be updated to a tag once we've released a new version of the stdlib)
• Updates the Package files to V2 Package
• Uses a minimal Prelude file to avoid parsing/scoping the whole stdlib during the compiler pipeline.

This improves the compiler performance:

Before:

$ time juvix typecheck Example.juvix
Well done! It type checks
juvix typecheck Example.juvix  4.50s user 0.05s system 99% cpu 4.564 total

After:

$ time juvix typecheck Example.juvix
Well done! It type checks
juvix typecheck Example.juvix  1.94s user 0.04s system 98% cpu 1.993 total