[Enhancement] Improving response of validators and reducing unnecessary calls to API server

[arteevraina]

Issue Description.

1. In Register Page, when text field is empty (for example: First Name , the validator responds with message like First Name cannot be left blank, But when the email field is empty it does not respond with Email cannot be left blank but rather it shows Not a valid Email Address). I think Not a valid Email Address should be shown when actually email address is invalid not when it is left blank.
   Possible Solution: Play with some conditions in the validator class.
2. In Login Page, we are not even validating the fields, though we are doing a check _formKey.currentState.validate() before hitting the API but that is not doing anything good since it is always validating to true. This is resulting in unnecessary API calls on the server.
   Possible Solution: use TextEditingController and validators in Text Fields in Login Page.
   After doing these changes some changes also need to be made in the unit tests for validators to test the new behaviour. If this gets approved, I am happy to chime in and fix this up.

Issue Severity

Medium

Does this issue needs immediate attention ?

Yes.

Are you willing to work on this issue ?

Yes.

[Sagar2366]

@arteevraina please use issue template and update all the required details.