Sends a site member an email with a link to set their password.
Important:
This function is in Developer Preview and is subject to change.
The sendResetPasswordEmail() function returns a Promise that resolves
when the set password link is emailed to the member.
The reset password link is valid for 3 hours, and it can be used only once. If the link expires, no changes are made to the password.
Login email of the member whose password will be set.