developing of plugin for partner metatags

REF: https://github.com/MenschDankeGmbH/gutscheinpony/issues/1103
not compelety.
This method must select an axtern value like https://github.com/MenschDankeGmbH/gutscheinpony/pull/1212/files#diff-70fae80b02b3a3d9b03d314d7eb4c41fR370 as far as no data from DB exists.