Added support for a pkgs argument to the pip state

- The pip state has been modified to allow a pkgs argument
- It receives a list of packages to install
- Version specification must be enclosed by quotes
- If pkgs is specified, name is ignored
- If requirements or editable is specified, pkgs is ignored
Merge pull request #19001 from mirath/feature/pip_pkgs

Added support for a pkgs argument to the pip state