Use scientific notation for big values inl labeled slider

[Czaki]

Closes #224

Use QLabel instead of QDoubleSpinBox for custom representation of big/small values.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 87.18%. Comparing base (0396d46) to head (5d87bc5).

Files	Patch %	Lines
src/superqt/sliders/_labeled.py	85.71%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #226      +/-   ##
==========================================
- Coverage   87.30%   87.18%   -0.13%     
==========================================
  Files          46       46              
  Lines        3332     3371      +39     
==========================================
+ Hits         2909     2939      +30     
- Misses        423      432       +9     

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[tlambert03]

basic idea looks good. lemme know when ready for a full review. How do you plan to manage when it switches into scientific notation?

[Czaki]

Currently, it depends on str(float), as for big values, on my machine it uses scientific notation. I need to check how universal it is.