User registration and login using email only

Note - we want to move to a email only system.

[x] Email is must when registering (any domain).
[ ] Convert all existing user who has no email's email to fake.<phone>@lipi.shop

Note - already users can login using email id.

[x] User trying to login with a phone number will be disallowed directly on the client side.
[x] Users can only login with email ID

Note - there is an email id verification system in place.

[x] Send verification mail after registration
[x] Adjust verification time limit to user friendly point.
[x] Users should be able to login even if email is not verified for a time threshold.
[x] After registering using email user get an email with a link, clicking the link takes them to a simple static page.

[x] Hide phone number from client on the edit-profile page
[x] User can update profile as usual
[x] Changing email will set email as unverified and send out another verification email to the new address

[x] User will input an email id after clicking forgot password. Link to reset password page would be sent via email.

Note - all old users registered using phone number. We cannot be sure if we have all their email id.

Note - we already pass user not verified flag to client.

[x] Hide phone number from page manage-employees and view-employee/employee:XX
[x] In page add-employee - contact number field will be email field. And we should mention how this email will be used to login
[x] Hide hire existing Lipi user as employee area

Extra checks

Related git issues - #1176 #1136