MediaSearch's filters `mimeType`, `imageSize` & `license` map directly to Cirrus search keywords `filemime`, `fileres` and `haslicense`.
I suggest we simply use the same keywords:
- it saves some code & complexity from mapping one thing to another and back
- it's more straightforward for those who know and use these keywords already
//Note: I think it'd also make sense to map `type` to `filetype`, although that one's slightly special because - for the categories&pages tab - it doesn't map to a cirrus keyword, but kicks off another type of search altogether. (out of scope for this ticket)//
Acceptance criteria:
[] the URL query param for licenses becomes `haslicense`
[] the URL query param for file types becomes `filemime`
[] the URL query param for images sizes becomes `fileres`