maint(common): common/test has both keyboards and fixtures/keyboards and other apparently web-only files

A few tidy-up items:
* Most (all?) files in /common/test/resources appear to be used only for web builds. These should be moved under web/src/test; do these files really need a separate package.json?
* Under /common/test, we have both keyboards/ and resources/keyboards/ folders. This is confusing. This may be resolved by addressing the point above
* Possibly should rename the folder to /common/tests to match other 'test' folder names.