Create lightweight plugin_action_scope.h containing only the enum class.
Replace #include <api/api_plugin.h> in eda_draw_frame.h with the new
header and a forward declaration of PLUGIN_ACTION.
This removes transitive includes wx/bmpbndl.h, wx/filename.h and
nlohmann/json_fwd.hpp from 79 TUs.
Also flip the dependence between json_schema_validator and kicommon,
and create a shared JSON_SCHEMA_VALIDATOR so that we don't have to
copy/paste the schema loading code as much
Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
Seth Hillbrand