Ruby Bindings: Implement Enumerable for iterable collections

[jackorp]

Implement including Enumerable and the #each method for iterable collections.

This allows for example to iterate over a package query:

require 'libdnf5/base'

base = Base::Base.new
base.setup()

repo_sack = base.get_repo_sack()
repo_sack.create_repos_from_system_configuration()

rq = Repo::RepoQuery.new(base)
rq.filter_id('rawhide')

repo_sack.load_repos(Repo::Repo::Type_AVAILABLE)

query = Rpm::PackageQuery.new(base)
query.filter_provides("rubygem(httparty)", Common::QueryCmp_EQ)

query.each # Returns => #<Enumerator: ...>
query.each do |pkg|
  puts pkg.get_name
end
# Prints => rubygem-httparty
# And Returns => #<Rpm::PackageSet:0x00007f14d9ecd9a8 @__swigtype__="_p_libdnf5__rpm__PackageSet">

Related issue: #1780

[jackorp]

I have implemented #each for collections that I could find, I was just looking for the implemented "begin" method, so not sure if I missed any collections that are also iterable.

Other collections like Reldep or AdvisorySet do not have tests in Ruby so I have not extended them. I can take a stab at creating them if the tests are desired.