feat(email): data mapping refactors and default template updates

See #1547 (closed)

• Refactored automated email template data mapping to use a common function sendEmailWithPreparedData from userCommsUtils.js
• Cleanup sendEmailWithPreparedData code
• Added a SQL migration query to replace the following variable placeholders as follows:

Email content - subject variable replacements

{{ currentUser }} - {{ senderName }}

{{ shortId }} - {{ manuscriptNumber }}

{{ articleTitle }} - {{ manuscriptTitle }}

Email content - body variable replacements

{{ currentUser }} - {{ senderName }}

{{ receiverName }} - {{ recipientName }}

{{ shortId }} - {{ manuscriptNumber }}

{{ articleTitle }} - {{ manuscriptTitle }}

{{{ appUrl }}} - {{{ loginLink }}}

{{{ manuscriptPageUrl }}} - {{{ manuscriptLink }}}

{{{ submissionLink }}} - {{{ manuscriptTitleLink }}}