Fix AI sitegen sideload images

[abhijitb]

Proposed changes

This PR fixes the issue where some/all of the images in the pattern grammar do not get replaced with the local copy of the image.

1. We were using regex to find images inside the <img> tag, but on checking the pattern grammar I saw that there were URLs like this also

<!-- wp:cover {"url":"https://images.unsplash.com/photo-1621945762389-d8012f045927?q=80&auto=format&fit=crop&ixlib=rb-4.1.0&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D&w=1200&h=&crop=","dimRatio":80,"isUserOverlayColor":true,"focalPoint":{"x":1,"y":0.24},"minHeight":605,"minHeightUnit":"px","customGradient":"linear-gradient(135deg,rgb(255,255,255) 44%,rgba(255,184,184,0) 100%)","sizeSlug":"full","className":"nfd-p-lg nfd-rounded-xl","layout":{"type":"constrained"}} -->

2. I also saw that some of the parameters in the image URL's were getting changed to & while storing and reading from the DB, which was then failing the replacing logic that we had in place.

Type of Change

Production

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update
• Refactoring / housekeeping (changes to files not directly related to functionality)

Development

• Tests
• Dependency update
• Environment update / refactoring
• Documentation Update

Visual

Checklist

• I have read the CONTRIBUTING doc
• I have viewed my change in a web-browser
• Linting and tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[github-actions]

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