refactor(server): pass hash version to computePasswordHash

[julio-lopez]

Motivation: Encapsulate details about the implementation of user profiles, in particular the password hashing scheme.

This is a cleanup, refactoring step in that direction.

No functional change.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 77.15%. Comparing base (cb455c6) to head (63df858). Report is 160 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3890      +/-   ##
==========================================
+ Coverage   75.86%   77.15%   +1.29%     
==========================================
  Files         470      482      +12     
  Lines       37301    28795    -8506     
==========================================
- Hits        28299    22218    -6081     
+ Misses       7071     4670    -2401     
+ Partials     1931     1907      -24     

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