Bug: GHCup missing dependencies

[peter-bread]

See https://www.haskell.org/ghcup/install/#system-requirements for all requirements.

Originally posted by @peter-bread in #74

Should these be installed in packages/manual/ghcup or in install#prime.

Also, if the option is for the package manager available, should these be install as dependency vs on-request.

[peter-bread]

This is actually a more general question about all manual install scripts: should they be responsible for their own dependencies?

[peter-bread]

This is actually a more general question about all manual install scripts: should they be responsible for their own dependencies?

Leaning towards yes...