New feature: Get author articles from OpenAlex

[ahasverus]

This PR fixes #30, #44 & #45.

In addition, functions querying OpenAlex API have been:

• renamed:

  • fp_retrieve_author_oa_id() > fp_get_openalex_author()
  • fp_retrieve_article_doi() > fp_get_openalex_doi()

• and refactored:

  • fp_get_openalex_author() = fp_oa_fetch_authors() + fp_oa_parse_authors()
  • fp_get_openalex_doi() = fp_oa_fetch_dois() + fp_oa_parse_dois()

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (fb52f0a) to head (0a29499).

Additional details and impacted files

@@            Coverage Diff             @@
##              main       #46    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files            9        14     +5     
  Lines          377       534   +157     
==========================================
+ Hits           377       534   +157     

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[ahasverus]

@nmouquet: here is the workflow proposed by this PR.

1. fp_get_openalex_author_id() retrieves the OpenAlex ID of the author
2. fp_get_openalex_author_works() retrieves the works of this author. Some filters are available (drop NA in DOI/journal and select work types)
3. fp_identify_duplicate_works() identifies the potential duplicate works by creating unique reference ID. Similar works will have the same ID. These duplicate works are just flagged not deleted.

N.B. The plot of the temporal trend of the ratios will be implemented in a different PR.