feat: change dataset publish validation from at least one required field to at least one field (required or not)

[jfcalvo]

Description

In this PR we are changing how dataset publish validation works moving from:

• At least one required field to be a valid publishable dataset.

To:

• At least one field (required or not) to be a valid publishable dataset.

Refs argilla-io/roadmap#21

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

• Modifying test suite.

Checklist

• I added relevant documentation
• I followed the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• I confirm My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• 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 91.30%. Comparing base (6c5d5e9) to head (3b49f6d).
Report is 1 commits behind head on feat/argilla-direct-feature-branch.

Additional details and impacted files

@@                         Coverage Diff                         @@
##           feat/argilla-direct-feature-branch    #5569   +/-   ##
===================================================================
  Coverage                               91.30%   91.30%           
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  Files                                     145      145           
  Lines                                    6037     6037           
===================================================================
  Hits                                     5512     5512           
  Misses                                    525      525           

Flag	Coverage Δ
argilla-server	91.30% <100.00%> (ø)

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