Declutter display of hyper-parameter labels in plots

[ablaom]

When tuning deeply nested hyper-parameters, the plots get horribly cluttered.

Before this PR:

After this PR:

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.44%. Comparing base (d4bd5c4) to head (1750557).
⚠️ Report is 2 commits behind head on dev.

Files with missing lines	Patch %	Lines
src/plotrecipes.jl	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #229      +/-   ##
==========================================
+ Coverage   87.34%   87.44%   +0.09%     
==========================================
  Files          13       13              
  Lines         664      677      +13     
==========================================
+ Hits          580      592      +12     
- Misses         84       85       +1     

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[OkonSamuel]

LGTM!!!. I love your solution @ablaom.
This is a tricky problem as MLJ does not place any limit on the length of a model parameter, but the defaults you used are sufficient for most cases. I don't think most people will have a model with the innermost parameter having length greater that 20.
Anyways for more complicated setup the user can always adjust the plot width.

[OkonSamuel]

Are the ellipsis unicode (i.e "\u2026" ) or just 3 dots?. If this isn't unicode ellipsis, we can get more space by using unicode ellipsis.

[ablaom]

It the single character unicode character.

[ablaom]

Thanks @OkonSamuel for your review.