Describe the bug
Harper flags multiple contiguous spaces as an error. This is usually the right thing to do, but in HTML such multiple spaces are condensed down to a single space and people use multiple spaces for formatting, aligning, indenting, etc.

I'm only talking about within tags that contain text. Harper ignores whitespace that's part of the HTML format.

To Reproduce
Steps to reproduce the behavior:

1. Open an HTML file in your harper-supporting editor.
2. Look for text with multiple spaces, or type in some extra spaces.
3. Note the squigglies.

Expected behavior
No squigglies for repeated spaces in text parts of HTML files.

Screenshots

Additional context
This might involve a general way of disabling specific lints for specific file formats, which will probably turn out to be useful elsewhere.