feat(frontend): write FieldVerificationService in TypeScript

[karrui]

Problem

This PR migrates the old verification.client.factory Angularjs module to FieldVerificationService in TypeScript.

Solution

Features:

• replace old verification.client.factory with FieldVerificationService

Tests

• Add unit tests for FieldVerificationService. Note that all the tests are for the happy path as there is no error handling in the services as of yet (all errors are handled outside the service, due to legacy AngularJS code and not worth effort to refactor yet)

Manual tests

• Create a form with no verified fields. The call to POST /transaction should return an empty object {}
• Create a form with some verified fields. The call to POST /transaction should return an object with expiry and transaction id.
• In a form with email verified fields, attempt to verify email. The OTP should be sent successfully to the email.
  • Provide an invalid OTP. Should show invalid OTP message below the OTP input field.
  • Correctly input OTP. Should successfully be verified.
• In a form with mobile verified fields, attempt to verify mobile. The OTP should be sent successfully to the number.
  • Provide an invalid OTP. Should show invalid OTP message below the OTP input field.
  • Correctly input OTP. Should successfully be verified.
• Should successfully submit form with verified fields as per normal