Puppet should ignore empty init.pp

Puppet6 will error if a module contains an empty init.pp. The module documentation says, "init.pp: Contains a class definition. The init.pp class, if used, is the main class of the module. This class's name must match the module's name."

So the init.pp file is optional, but we don't specify whether the file can exist, but be empty or if it only contains a defined type.

We discovered in MODULES-7854 that some people may have empty init.pp and puppet should be more lenient. For now, we removed the empty init.pp from the rspec-puppet's module fixtures.

/cc henrik.lindberg, kris.bosland, ben.ford, chuck, eric.sorenson