profiles: Generalize "hooks" for 'profile-derivation'.
* guix/profiles.scm (info-dir-file): Remove (null? (manifest-entries
manifest)) test.
(ca-certificate-bundle): Likewise.
(ghc-package-cache-file): Turn 'if' into 'and', and remove second
arm.
(%default-profile-hooks): New variable.
(profile-derivation): Remove #:info-dir?, #:ghc-package-cache?, and
#:ca-certificate-bundle?. Add #:hooks. Iterate over HOOKS. Adjust
'inputs' accordingly.
* guix/scripts/package.scm (guix-package): Adjust 'profile-derivation'
call accordingly.
* tests/packages.scm ("--search-paths with pattern"): Likewise.
* tests/profiles.scm ("profile-derivation",
"profile-derivation, inputs"): Likewise.