Refactor: Reuse rpcv6 juno_version handler for v7 and v8

[hudem1]

rpc pkg cleanup according to #2437

All 3 rpc versions' juno_version endpoint reference the same handler method in the "master" handler

[rianhughes]

Importing the "errors" pkg should fix the tests and lint errors. Approving now to unblock this PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.71%. Comparing base (80c2b5c) to head (a6de3ea).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2471      +/-   ##
==========================================
- Coverage   74.76%   74.71%   -0.05%     
==========================================
  Files         139      139              
  Lines       16741    16734       -7     
==========================================
- Hits        12516    12503      -13     
- Misses       3389     3396       +7     
+ Partials      836      835       -1     

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