feat(imagekit): add modifiers and improve docs

[abhinavr4]

Added-

1. Detailed documentation for ImageKit provider.
2. Names for ImageKit transformations - provider modifiers.
3. Playground examples.

Relevant issue - #271

[pi0]

Thanks for the improvements!

[codecov-commenter]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 59.50%. Comparing base (d9aeae2) to head (343b03a).
⚠️ Report is 1178 commits behind head on main.

Files with missing lines	Patch %	Lines
src/runtime/providers/imagekit.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #336      +/-   ##
==========================================
+ Coverage   59.36%   59.50%   +0.13%     
==========================================
  Files          26       26              
  Lines         598      600       +2     
  Branches      149      187      +38     
==========================================
+ Hits          355      357       +2     
  Misses        243      243              

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