Search for item type in itypes when not found in Item_factory::m_templates because newly created artifacts add their itype only to itypes and not to Item_factory::m_templates.

Removed the c_str call whose result is converted to a std::string anyway.
Merge remote-tracking branch 'dda/pr/7646' into dda-master

* dda/pr/7646:
  Search for item type in itypes when not found in Item_factory::m_templates because newly created artifacts add their itype only to itypes and not to Item_factory::m_templates.