test that unchanged icons work still for projects, neighborhoods, and users
test that new large icons show in 1.5x/2x, and that newly uploaded small icons don't scale incorrectly. Non-square icons will get white padding to square them out, that's already been the case.
the neighborhood template changes can be tested by going to a nbhd admin page and putting something like this in the template section. Then register a new project in the nbhd, and it'll be used.
In branch db/8143. QA:
{ "icon": { "url": "https://forge-allura.apache.org/p/allura/wiki/Home/attachment/white_asf_logo.png", "filename": "test-icon.png" } }Merged.