Standardize JCMA/CCMA emails validations to align with Cloud accepted emails

Suggestion

Standardize JCMA/CCMA emails validations to align with Cloud accepted emails. Sometimes we see migrations fail due to invalid emails that pass the JCMA/CCMA email validation. Some examples are emails with commas or emails that have the domain example.com.

One example in the logs for JMCA is

2022-04-20 13:20:26,195+0000 pool-61-thread-8 INFO admin 638x165x4 b8p6mp 127.0.01 /rest/plugins/1.0/available/featured [c.a.j.m.tracking.polling.StatusPoller] Migration <migrationId> failed in stage user: Failed to validate migration request: BAD_REQUEST response from UMS: 104: One or more users have an invalid email address

It would make it a better user experience if these pre-checks captured these emails instead of waiting for the migration to fail after a few mins/hours.

Additionally, please document the exact validation rules we use so that admins can self help and clean emails in a less reactive way.