Merge branch 'json-local-users' into 'master'

feat: new LocalUserDetailsLoader for populating local-users store

New optional user interface for populating the LocalUserDetailsManagerImpl instance provided in the `local-users` profile. The default configuration will still use the existing `LocalUserDetailsAttributesMapper.Default` implementation.

To switch to the new loader, set the `edu.wisc.uwss.local.userDetailsLoader.enabled` Environment property to true. The default resource loaded is edu/wisc/uwss/local/local-users.json (classpath), to change that location set the `edu.wisc.uwss.local.userDetailsLoader.resource` Environment property to a valid Spring Resource expression ('classpath:', 'file:', etc).

cc: @ahoffmann @paul.erickson @bhill6 @lyle @andrew-summers @apatwary @cknuth 

See merge request !19