Migrate client-side utility functions to a separate module

[tieneupin]

Fully resolves issue #446 by migrating the client-side utility functions into a separate module named murfey.util.client, thereby preventing unwanted import chains. Also adds unit tests for the migrated read_config() and _get_visit_list() functions.

Additionally, added some logic into read_config() to allow us to specify config files directly using MURFEY_CLIENT_CONFIGURATION (same naming pattern as MURFEY_MACHINE_CONFIGURATION and MURFEY_SECURITY_CONFIGURATION) so that the file name doesn't have to default to .murfey.

Verification Checks

• Server-side commands such as murfey.create_db and murfey.add_user no longer throw the "Client config not found" warning
• TUI workflows run
  • SPA
  • Tomo
  • CLEM
• Web UI workflows run
  • SPA
  • Tomo
  • CLEM

[codecov]

Codecov Report

Attention: Patch coverage is 67.07317% with 54 lines in your changes missing coverage. Please review.

Project coverage is 30.24%. Comparing base (e150506) to head (a59248e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #563      +/-   ##
==========================================
+ Coverage   30.20%   30.24%   +0.04%     
==========================================
  Files          79       80       +1     
  Lines       10500    10496       -4     
  Branches     1401     1401              
==========================================
+ Hits         3171     3174       +3     
+ Misses       7223     7217       -6     
+ Partials      106      105       -1     

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