Further improve compatibility tool design and UX

[westonruter]

Summary

See #2316. Follow up on #3505.

Improve table row styling (before/after)

• Eliminate zebra striping (shades of red) for new errors is eliminated in favor of gray borders, to align with comments.
• Improve column widths.

Ensure bulk accept/reject buttons cause new state to be cleared for validation errors on validated URL screen (before/after)

This aligns the behavior for when just changing the status in the dropdown.

Improve sources list (before/after)

• Put the entire source stack in a table to ensure alignment.
• Give details > summary a cursor:pointer and disable user-select to prevent text from being selected when clicking.
• Improve summary text to indicate the contents is a source stack (not “possible sources”).

Linkify Element Attribute Values (before/after)

To facilitate investigating the functionality of a script or stylesheet that is being excluded, the URL attribute value is linked to open it in a new tab:

Improve styling of validated URL errors list table (before/after)

• Improve color of “Showing” message
• Fix alignment of expand/collapse all button in column header (fixes Expand/collapse all header arrows are not aligned properly #2078)
• Improve column widths.

Improve styling of validation error list table (before/after)

• Align styling with Comments list table (removing underlines from hyperlinks).
• Shorten “Found URLs” to just “URLs”
• Add gray borders between each row (aligning with Comments list table design)

Improve design of error details shown on the single validation error view (before/after)

• Fix positioning of accept/reject button.
• Show both accept and reject buttons when the error is in a new state.

Checklist

• My pull request is addressing an open issue (please create one otherwise).
• My code is tested and passes existing tests.
• My code follows the Engineering Guidelines (updates are often made to the guidelines, check it out periodically).

[amedina]

Ship it!