Integrate CrossrefReferenceLinking plugin functionality into Crossref plugin

[bozana]

The functionality from the CrossrefReferenceLinking plugin (https://github.com/pkp/crossrefReferenceLinking) should be moved/integrated into the Crossref plugin (https://github.com/pkp/crossref-ojs).

The export and deposit of citations, if they exist, is already considered here: #11590.

To-Do:
Get DOIs for citations, especially if structured citations are not used, when citations are parsed and saved in the DB, and after they are registered with Crossref.
Display found citation DOI for the reader, if the raw citation does not already contain it.

Also, the changes here could be considered for OPS too, s. also pkp/crossrefReferenceLinking#45.

PRs:

• pkp/pkp-lib#12104 try to extract DOI from a citation also when metada… #12348
• pkp/pkp-lib#12104 move CrossrefReferenceLinking functionalities to Crossref plugin crossref-ojs#87

[bozana]

Hi @ewhanson, this is ready for review. If there is something and you manage to fix/change/improve before I am back, please do. Else, first when I am back :-)
Thanks a lot!

[bozana]

Hi @ewhanson, I am back and wanted to see how is the situation with this issue... :-)