Add reporting of iOS logins migration metrics

[lougeniaC64]

Fixes #4473.

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• Quality: This PR builds and tests run cleanly
  • Note:
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• Tests: This PR includes thorough tests or an explanation of why it does not
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• Dependencies: This PR follows our dependency management guidelines
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[codecov-commenter]

Codecov Report

Merging #4545 (8977425) into logins-per-field-encryption (d80ee73) will not change coverage.
The diff coverage is n/a.

@@                     Coverage Diff                      @@
##           logins-per-field-encryption    #4545   +/-   ##
============================================================
  Coverage                        78.81%   78.81%           
============================================================
  Files                               47       47           
  Lines                             4758     4758           
============================================================
  Hits                              3750     3750           
  Misses                            1008     1008           

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[skhamis]

This looks good to me! Thanks for adding tests for this!

Edit: Btw, the dependency test failings don't seem related to this PR