Fixed broken oauth2 login for operator (#1217)

This PR includes many fixes and refactors for oauth2 authentication and
login endpoints, ie:

- Invalid login returns `403` instead of `500` error
- Removed the session token from console/operator `user credentials
  login`, `oauth flow login` and `change-password` api responses
- Removed session token from localStorage
- Added styles for oauth_callback page and display more descriptive
  errors for debugging
- Success logins returns `204` instead of `200`
- Removed unused swagger apis and code from both, operator and console
  projects
- Operator `Oauth2` login flow was not validating anything, now it does

Signed-off-by: Lenin Alevski <alevsk.8772@gmail.com>

restapi/error.go

@@ -14,6 +14,7 @@ var (
 	// ErrorGeneric is a generic error message
 	ErrorGeneric               = errors.New("an error occurred, please try again")
 	errInvalidCredentials      = errors.New("invalid Login")
+	errForbidden               = errors.New("403 Forbidden")
 	errorGenericInvalidSession = errors.New("invalid session")
 	// ErrorGenericNotFound Generic error for not found
 	ErrorGenericNotFound = errors.New("not found")
@@ -54,6 +55,9 @@ func prepareError(err ...error) *models.Error {
 		frame := getFrame(2)
 		fileParts := strings.Split(frame.File, "/")
 		LogError("original error -> (%s:%d: %v)", fileParts[len(fileParts)-1], frame.Line, err[0])
+		if err[0].Error() == errForbidden.Error() {
+			errorCode = 403
+		}
 		if err[0] == ErrorGenericNotFound {
 			errorCode = 404
 			errorMessage = ErrorGenericNotFound.Error()