3464 add modified/modifiedBy to CoLDP exporter

[gdower]

This adds modified date and modifiedBy (as either orcid or name) to the coldp exporter for all files
It also changes the User.orcid to use identifier instead of cache like the Person model

[codecov-commenter]

Codecov Report

Patch coverage: 72.72% and no project coverage change.

Comparison is base (78b9cea) 85.84% compared to head (a692fa1) 85.84%.

❗ Current head a692fa1 differs from pull request most recent head 5da79e3. Consider uploading reports for the commit 5da79e3 to get more accurate results

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Additional details and impacted files

@@             Coverage Diff              @@
##           development    #3479   +/-   ##
============================================
  Coverage        85.84%   85.84%           
============================================
  Files             2005     2005           
  Lines            72463    72475   +12     
============================================
+ Hits             62203    62214   +11     
- Misses           10260    10261    +1     

Impacted Files	Coverage Δ
lib/export/coldp/files/description.rb	46.15% <33.33%> (ø)
lib/export/coldp/files/vernacular_name.rb	45.00% <33.33%> (ø)
lib/export/coldp/files/taxon.rb	50.00% <50.00%> (ø)
lib/export/coldp/files/name.rb	46.98% <60.00%> (ø)
lib/export/coldp/files/synonym.rb	30.76% <66.66%> (ø)
lib/export/coldp.rb	81.69% <93.75%> (+2.02%)	⬆️
app/models/person.rb	89.95% <100.00%> (ø)

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[mjy]

@gdower looks great, thanks. A couple very minor bits/Qs.