Prepare DB for structured citations to come

[bozana]

DB should be prepared so that the work on structured citation can come later, any time, and would not require a DB upgrade, so that structured citations can be merged without waiting for next major release where DB upgrades are allowed.
Structured citations require following DB changes:
Removing the column setting_type in the table citation_settings, because citations are moved to the EntityDAO. This column will not be removed right now, but made nullable, so that old code and classes CitationDAO and Citation can still work. After structured citations are merged, this column can be removed in the next major release.
Removing the setting citationsRaw from the publication_settings table. This will be done now, for 3.5.0. The raw citations for publication object will be constructed by concatenating the each/every single raw citation.
Note: Multilingual citations would require more DB changes, e.g. moving the entries from the column raw_citation from the table citations into the citation_settings table, but for now multiple citations will not be considered, thus these changes will be done once the work on multilingual citations starts/is done.

PRs:
stable-3_5_0:

• pkp/pkp-lib#11238 prepare DB for structured citations #11239
• pkp/pkp-lib#11238 prepare DB for structured citations ojs#4819
• pkp/pkp-lib#11238 prepare DB for structured citations omp#1947
• pkp/pkp-lib#11238 prepare DB for structured citations ops#948
• pkp/pkp-lib#11238 use publication citations data googleScholar#28
• pkp/pkp-lib#11238 use publication citations data jatsTemplate#85

main:

• pkp/pkp-lib#11238 prepare DB for structured citations #11278
• pkp/pkp-lib#11238 prepare DB for structured citations ojs#4835
• pkp/pkp-lib#11238 prepare DB for structured citations omp#1955
• pkp/pkp-lib#11238 prepare DB for structured citations ops#957
• pkp/pkp-lib#11238 use publication citations data googleScholar#29
• pkp/pkp-lib#11238 use publication citations data jatsTemplate#86

pkp/crossrefReferenceLinking#31
pkp/medra#44

[bozana]

Hi @asmecher, these are the minimal DB changes needed for 3.5.0, so that structured citations can come later at any point.
Could you please review the PRs?
Thanks a lot!

[bozana]

Hmmm... @asmecher, do you think the hook renaming should also take place now, before 3.5.0:
CitationDAO::afterImportCitations -> Citation::importCitations::after ?

[asmecher]

Hmmm... @asmecher, do you think the hook renaming should also take place now, before 3.5.0:

Yes, that's a good idea; it's unlikely to be used, but add the old one to the Hook::addUnsupportedHooks list in lib/pkp/classes/core/PKPApplication.php; at the same time, make the switch from Hook::run to Hook::call per these conventions. (All new hooks should use Hook::run, which isn't 100% backwards compatible.)