Person-Person: Add converse relationship types and display (#1458), add new "ambiguity" category (#1457)

[blms]

In this PR

Per #1458:

• Show read-only list on the Person admin for reverse Person-Person relationships
  • Rename existing one to "Related People (input manually)" and name the second "Related People (populated automatically)"
• Add field for "converse" type names for relationship types
  • Populate converse_name from provided spreadsheet (for those relationships that are asymmetrical)
  • Display the converse_name on the People pages' read-only reverse Person-Person sections

Per #1457:

• Add new PersonPersonRelationType category called "Ambiguity" to track relationships of ambiguity, such as "possibly the same person" and "not to be confused with", and populate with those two types (both symmetrical so no converse name required)

Notes

All language, naming, and labeling was discussed, iterated, and approved in 9/13 meeting

[codecov[bot]]

Codecov Report

Merging #1462 (ed2928d) into develop (f4dc0f3) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #1462   +/-   ##
========================================
  Coverage    98.70%   98.70%           
========================================
  Files          206      208    +2     
  Lines        11498    11537   +39     
========================================
+ Hits         11349    11388   +39     
  Misses         149      149