Post different event for client-side javascript auto-timer submit

We have a number of reports of unexpected timer behaviour for timed tests, where the time displayed is reported to be incorrect, or the test has been prematurely submitted.

To troubleshoot these further, it would be helpful to have a different event logged when the assessment is submitted the the client-side javascript timer, as compared to when the assessment is submitted by the user actually clicking on Submit for Grading.

Current events are:

"sam.assessment.submit" (client-side submit)
"sam.assessment.submit.via_url" (taken via a published URL)
"sam.assessment.thread_submit" (server-side timer thread submission)

Possible new event name:

sam.assessment.timer_submit for assessments submitted the client-side javascript timer.