feat: enhance loading states in data loader hooks

[philibea]

Adds distinction between initial loading (isLoading) and ongoing fetching (isFetching) to provide more granular control over loading states in data loader hooks.

[changeset-bot]

⚠️ No Changeset found

Latest commit: c57142f

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[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.96%. Comparing base (6833499) to head (c57142f).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/use-dataloader/src/useDataLoader.ts	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2858      +/-   ##
==========================================
+ Coverage   68.85%   68.96%   +0.10%     
==========================================
  Files          44       44              
  Lines        1294     1305      +11     
  Branches      181      185       +4     
==========================================
+ Hits          891      900       +9     
- Misses        380      382       +2     
  Partials       23       23              

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