feat(graph): implement easier "userSubmissions" API

Author: pan93412

graph/question.graphqls

@@ -63,6 +63,11 @@ extend type Mutation {
 extend type Question {
   referenceAnswerResult: SQLExecutionResult! @scope(scope: "question:read")
 
+  """
+  List of your submissions for this question.
+  """
+  userSubmissions: [Submission!]!
+
   """
   Have you tried to solve the question?
   """
@@ -74,51 +79,6 @@ extend type Question {
   solved: Boolean!
 }
 
-extend type User {
-  """
-  Get all submissions of a question.
-  """
-  submissionsOfQuestion(
-    """
-    The question ID.
-    """
-    questionID: ID!,
-    """
-    Returns the elements in the list that come after the specified cursor.
-    """
-    after: Cursor
-
-    """
-    Returns the first _n_ elements from the list.
-    """
-    first: Int
-
-    """
-    Returns the elements in the list that come before the specified cursor.
-    """
-    before: Cursor
-
-    """
-    Returns the last _n_ elements from the list.
-    """
-    last: Int
-
-    """
-    The where input to filter the submissions.
-    """
-    where: SubmissionsOfQuestionWhereInput
-
-    """
-    The order by input to order the submissions.
-    """
-    orderBy: SubmissionOrder
-  ): SubmissionConnection!
-}
-
-input SubmissionsOfQuestionWhereInput {
-  status: SubmissionStatus
-}
-
 type SQLExecutionResult {
   columns: [String!]!
   rows: [[String!]!]!