* fix : split out the interface from the TwoFactorAuthenticationValidator into separate file.
* fix: replacing IUserService.TwoFactorEnabled with ITwoFactorEnabledQuery
* fix: combined logic for both bulk and single user look ups for TwoFactorIsEnabledQuery.
* fix: return two factor provider enabled on CanGenerate() method.
* tech debt: modfifying MFA providers to call the database less to validate if two factor is enabled.
* tech debt: removed unused service from AuthenticatorTokenProvider
* doc: added documentation to ITwoFactorProviderUsers
* doc: updated comments for TwoFactorIsEnabled impl
* test: fixing tests for ITwoFactorIsEnabledQuery
* test: updating tests to have correct DI and removing test for automatic email of TOTP.
* test: adding better test coverage
refactor(TwoFactorAuthentication): Remove references to old Duo SDK version 2 code and replace them with the Duo SDK version 4 supported library DuoUniversal code.
Increased unit test coverage in the Two Factor Authentication code space. We opted to use DI instead of Inheritance for the Duo and OrganizaitonDuo two factor tokens to increase testability, since creating a testing mock of the Duo.Client was non-trivial.
Reviewed-by: @JaredSnider-Bitwarden
