Send pull request reviewer email address to Jira Cloud dev info

Jira Cloud is able to link Bitbucket DC users with Jira Cloud (Atlassian ID) users if they use the same email address.

Bitbucket DC currently sends a user's email address when they are the pull request author but does not send the email address when they are a pull request reviewer (because the original spec didn't support sending an email for reviewers).

Send the email address of pull request reviewers to Jira Cloud so the cloud data can link users properly.