Using outputsToInstall the intended behaviour of including host and dnsutils
when bind is installed can be implemented instead of using symlinks to fix
installing all outputs individually with nix-env.
Fixes#19761.
- add missing types in module definitions
- add missing 'defaultText' in module definitions
- wrap example with 'literalExample' where necessary in module definitions
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
