fix: allowedClasses whitelist ignored if tag is wildcard

[anak-dev]

Summary

When using the * selector for a allowedClasses option, the rule is ignored if it is regex. It works if it is not regex or if the selector specifies a specific html tag. The above examples would produce the expected result if the * was replaced with a p, for example.

Closes #673

What are the specific steps to test this change?

const exampleHtml = '<p class="main-color-#4ea832">Text with color</p>';

console.log(
  sanitizeHtml(exampleHtml, {
    allowedClasses: {
      '*': [/^main-color-#[0-9A-Fa-f]{6}$/],
    },
  })
);

The result should include the class instead of removing it.

<p class="main-color-#4ea832">Text with color</p>

What kind of change does this PR introduce?

(Check at least one)

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

[boutell]

Thank you!