Fix [class*=foo] with HTML extractor

[Gaelan]

Proposed changes

Previously, the values of the id and class attributes were stored only as ids and classes respectively, which meant selectors like [class*=foo] were spuriously removed because "foo" is only treated as a class value, not an attribute value. This PR fixes that by unconditionally adding attributes to the generic attribute list, then also adding them to the id/class lists if appropriate.

Types of changes

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• 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)

Checklist

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• Lint and unit tests pass locally with my changes
  • Some unrelated tests are failing with include errors - I suspect I've done something wrong with Lerna on my machine and it's unrelated, but let's see what CI says.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
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[github-actions]

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[Gaelan]

Still would be great to have this merged!