Login & Signup enhancements

**Describe the bug**
1. No visual feedback like loader when logging in or signing up.
2. No validation of data or form fields on client-side or server-side. I can create users by submitting below details 😲
3. In the above screenshot, you can see the signup form has `Login` header.
4. Signing up should automatically login user which is better UX

**To Reproduce**
Steps to reproduce the behavior:
1. Go to log in or signup page
2. Try to create user
3. You can find above-listed issues or bugs

### Expected Behaviour
1. Add a loader when the form is being submitted.
2. Add client-side form validation and also do same in serverside
3. Fix signup form header
4. On backend implement automatically login user when user signs up and reflect same on frontend side also