fix(auth): E-Mail capitalization issue

[DollyXSoul]

Fixes #1740

This issue affects email in three places where user needs to enter the email - during registration ,login and forgot-password page.
To fix that we convert the email to lowercase before processing or sending to db.

-> During the user registration , the email entered by user is converted to lowercase and then stored in db.

->Similarly , in forgot-password , so again as we do a check in db if given email exists or not, so again make given user email to lowercase.

-> And in login user can enter email or username(already in lowercase) so if we convert user-input to lowercase it won't affect login using username.

[AmruthPillai]

@DollyXSoul Wouldn't there be some need to case-insensitivize the backend auth checks as well?

[DollyXSoul]

@AmruthPillai Yes you are right I forgot about that. Should I just convert email to lowercase on backend as well , or you have a better suggestion to do this ??