Set substitution for librepo handle from Base Vars

It allows substitutions in mirrorlist.

Additionally it marks method of Repo class as deprecated, because it is
not required anymore.

Closes: #761

include/libdnf5/repo/repo.hpp

@@ -327,6 +327,7 @@ class Repo {
  // @replaces libdnf:repo/Repo.hpp:method:Repo.getMirrors()
  std::vector<std::string> get_mirrors() const;
 
+ /// @deprecated It is redundant because repo class has direct access to Base and Vars
  /// Sets substitutions. Substitutions are used to substitute variables in repository configuration.
  // @replaces libdnf:repo/Repo.hpp:method:Repo.setSubstitutions(const std::map<std::string, std::string> & substitutions)
  void set_substitutions(const std::map<std::string, std::string> & substitutions);

libdnf5/repo/repo_downloader.cpp

@@ -511,9 +511,13 @@ void RepoDownloader::common_handle_setup(LibrepoHandle & h) {
  h.set_opt(LRO_YUMSLIST, repomd_substs);
 
  LrUrlVars * substs = nullptr;
+ // Deprecated, we have direct access to base, therefore we don't need to set explicitly substitutions
  for (const auto & item : substitutions) {
  substs = lr_urlvars_set(substs, item.first.c_str(), item.second.c_str());
  }
+ for (const auto & item : base->get_vars()->get_variables()) {
+ substs = lr_urlvars_set(substs, item.first.c_str(), item.second.value.c_str());
+ }
  h.set_opt(LRO_VARSUB, substs);
 
 #ifdef LRO_SUPPORTS_CACHEDIR