feat: add picture-lqip format with low quality base64 image

[pzerelles]

• Quick Checklist

• I have read the contributing guidelines
• I have written new tests, as applicable (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• I have added a changeset, if applicable

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  Feature

• What is the new behavior (if this is a feature change)?
  The picture output can have a low quality base64 image.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this
  PR?)
  No

• Other information:

[changeset-bot]

🦋 Changeset detected

Latest commit: dfc32a9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
imagetools-core	Patch
vite-imagetools	Patch

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[codecov]

Codecov Report

Attention: Patch coverage is 94.44444% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 94.17%. Comparing base (dc2f16f) to head (dfc32a9).

Files	Patch %	Lines
packages/core/src/output-formats.ts	94.11%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #662   +/-   ##
=======================================
  Coverage   94.17%   94.17%           
=======================================
  Files          33       33           
  Lines        1235     1270   +35     
  Branches      206      212    +6     
=======================================
+ Hits         1163     1196   +33     
- Misses         72       74    +2     

Flag	Coverage Δ
imagetools-core	94.17% <94.44%> (+<0.01%)	⬆️
vite-imagetools	94.17% <94.44%> (+<0.01%)	⬆️

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[benmccann]

If I understood the code here correctly, it looks like this isn't really transforming the image in a way that makes it much smaller (e.g. to display just the dominant background color). I think if we were going to add a feature like this we should do it with different transforms that shrink the image in various ways as mentioned in #86 (comment). We don't have to add them all off the bat, but it might be nice to have two options people could choose between to help us figure out the API

[pzerelles]

It actually takes the smallest size that you specify in the transform for the low quality preview.