rewrite login end-points to use unified service

[pythys]

this depends on first approving this PR on the moqui framework

[jonesde]

From a read through the code changes there are changes to the functionality so I am not confident in merging this until some testing is done of the various flows involved in login with and without a second factor required, and with correct and incorrect password and MFA code.

If someone else would like to help with this, please list the test scenarios you run and the results. I'll get to this sooner or later but am ill right now, and I see this as a lower priority as it is a code de-dup/cleanup effort more than a needed functional change.