Improve error handling of Mass Email Volunteers page

[davidhabib]

In VOL_CTRL_SendBulkEmail.SendEmail(), the error handling is enumerating over list<Messaging.SendEmailError>. Within this enumeration loop, it is querying for Contact names, one record at a time. This can lead to hitting soql limit errors. This logic needs to be redesigned to only query once for all the contact names at once.

[davidhabib]

**lurch: add

[LurchTheButler]

Tracking W-021557