QDR: PID bug fixes

[qqmyers]

What this PR does / why we need it:
Multiple small bug fixes/updates related to the PID handling and MDC citation retrieval code:

• avoid deprecated new URL call
• use correct PID setting when calling MDC API for citations
• make DOI comparisons case insensitive
• also insensitive in managed/excluded lists
• simplify parsing of DOIs in citations
• avoid one empty entry in managed/excluded sets when there are no PIDs listed.
• return correct type for DataCiteDOIProvider
• add is-supplement-to relationship (was supplements only)

Which issue(s) this PR closes:

Closes #10635

Special notes for your reviewer:

Suggestions on how to test this: The main tests would be to confirm that MDC citation retrieval works and that using a shoulder in lower/mixed case works, or vice-versa, that typing DOIs with lower case when the shoulder is upper case works (.e.g. /dataset.xhtml?persistentId=doi:10.33564/fk2LCUIJZ and /dataset.xhtml?persistentId=doi:10.33564/FK2LCUIJZ both resolve to the dataset page).

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

Is there a release notes update needed for this change?: included

Additional documentation:

[coveralls]

coverage: 20.878% (+0.009%) from 20.869%
when pulling a7e0d87 on QualitativeDataRepository:QDR-PIDBugFixes
into a0cb73d on IQSS:develop.

[ofahimIQSS]

Fix looks good - merging PR.
Testing of 10708.docx