Change resource table to be based on mime type

[tw4l]

Follow-up to #1689

Instead of using resource types, let's use the first half of mime types now, with a few manual substitutions to ensure that favicons, javascript, html, and stylesheets are put into better categories than just e.g. text.

[tw4l]

Converted to draft because there's an issue where if a category exists for replay but not crawl, it throws an uncaught TypeError

[tw4l]

TypeErrors fixed, this is now ready for review

[tw4l]

Switched to iterating through qaResources because there are frequently keys in qaResources that are not in crawlResources but not the other way around that I've seen.

[ikreymer]

Added a few more improvements, incorporating the resourceType as follows:

• if resourceType is script, stylesheet, image, font, use that definitively, instead of mime
• if resourceType is fetch/xhr, also check for extension, specifically for images, which might have text/html mime, especially for 404s
• also check for extension for json
• also check for pdf by type + extension
• categorize 'ping' as 'other'
• continue to use first part of mime as fallback