PXP-10708 Add coremetadata endpoint

[paulineribeyre]

Jira Ticket: PXP-10708

Move the https://github.com/uc-cdis/pidgin functionality to peregrine

The 1st commit is a copy/paste of the pidgin codebase and unit tests into peregrine (since all pidgin does is make requests to peregrine). The other commits are small changes:

• integrate it as a new peregrine endpoint /coremetadata
• update the logic to make a direct graphql query instead of an API call to peregrine
• new endpoint unit test
• a small improvement to the citation generation so we don’t end up with “None None” citations on the portal

New Features

• Add the /coremetadata endpoint, replacing the pidgin service

Improvements

• Improve the format of the citation automatically generated by the /coremetadata endpoint

Deployment changes

• The pidgin service can be removed if data-portal is on version 5.4.2/2023.05 or newer. Its functionalities are available at peregrine's /coremetadata endpoint
• ASK AN ADMINISTRATOR TO DELETE THE PIDGIN DEPLOYMENT if you remove pidgin. This is NOT automatic

[github-actions[bot]]

The style in this PR agrees with black. :heavy_check_mark:

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