refactor: move API errors folder structure

[jfcalvo]

Description

This PR include changes moving API errors to follow this structure:

/api
  /errors
    /v1
      ...

The behavior has not been changed.

Refs #4868

Type of change

(Please delete options that are not relevant. Remember to title the PR according to the type of change)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (change restructuring the codebase without changing functionality)
• Improvement (change adding some improvement to an existing functionality)
• Documentation update

How Has This Been Tested

(Please describe the tests that you ran to verify your changes. And ideally, reference tests)

• Test should be passing as before.

Checklist

• I added relevant documentation
• follows the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.40%. Comparing base (82b6811) to head (f4bd40c).

Additional details and impacted files

@@                             Coverage Diff                             @@
##           refactor/api-folder-structure-improvements    #4957   +/-   ##
===========================================================================
  Coverage                                       91.40%   91.40%           
===========================================================================
  Files                                             136      136           
  Lines                                            5820     5820           
===========================================================================
  Hits                                             5320     5320           
  Misses                                            500      500           

Flag	Coverage Δ
argilla-server	91.40% <100.00%> (ø)

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