[Feature] Refine design for referencing other tools

[antross]

With the addition of the ability to link to the Elements panel, we're starting to end up with a variety of potential references to different tools to help developers get context on hints in order to fix them.

Filing this task per @ststimac's request to take all of these into consideration as we're updating our browser extension design to help provide a clear and consistent experience.

Possible references for a hint:

• External site (for documentation)
• Inline code snippet (for partial original source code or HTML reference)
• Sources panel (for full original source code)
• Elements panel (for related or originating element in the DOM)
• Network panel? (if possible; for HTTP headers related to a request)