[GraphQL] Add create direct upload mutation

app/graphql/schema.graphql

@@ -40,6 +40,52 @@ GeoJSON coordinates
 """
 scalar Coordinates
 
+"""
+Autogenerated input type of CreateDirectUpload
+"""
+input CreateDirectUploadInput {
+  """
+  File size (bytes)
+  """
+  byteSize: Int!
+
+  """
+  MD5 file checksum as base64
+  """
+  checksum: String!
+
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  File content type
+  """
+  contentType: String!
+
+  """
+  Dossier ID
+  """
+  dossierId: ID!
+
+  """
+  Original file name
+  """
+  filename: String!
+}
+
+"""
+Autogenerated return type of CreateDirectUpload
+"""
+type CreateDirectUploadPayload {
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+  directUpload: DirectUpload!
+}
+
 type DateChamp implements Champ {
   id: ID!
   label: String!
@@ -131,6 +177,31 @@ enum DemarcheState {
   publiee
 }
 
+"""
+Represents direct upload credentials
+"""
+type DirectUpload {
+  """
+  Created blob record ID
+  """
+  blobId: ID!
+
+  """
+  HTTP request headers (JSON-encoded)
+  """
+  headers: String!
+
+  """
+  Created blob record signed ID
+  """
+  signedBlobId: ID!
+
+  """
+  Upload URL
+  """
+  url: String!
+}
+
 """
 Un dossier
 """
@@ -324,6 +395,10 @@ type MultipleDropDownListChamp implements Champ {
 }
 
 type Mutation {
+  """
+  File information required to prepare a direct upload
+  """
+  createDirectUpload(input: CreateDirectUploadInput!): CreateDirectUploadPayload
 }
 
 """