Split regex in Create a new issue handler

As of now, only emails creating comments can have regex settings that allow to truncate the irrelevant part of the message. It would be useful to be able to to the same when creating new issues from email.

Example use case:
JIRA is used as a support system. If the support team is contacted by their customer, they can send to them an email with the body beginning with something like:

*--
Please write above this line.

Dear user,
Thanks for contacting support.
Please enter your issue description and attach relevant screenshots.

Thanks,
Your support team.

--*

Reply to that email is received by Jira and triggers creating a new issue, with only the text above *-- as description.