Fix ObjectType casing and conflict between Relation and RelationMetadata (#9849)

Fixes #9827 

Also uncovered a conflict with `@objectType('Relation')` and
`@objectType('relation)`

I don't want to address it in this PR so I will create a followup issue
when we close this but I think there's a confusion between
Relation/RelationMetadata, it's unclear what is what

---------

Co-authored-by: Antoine Moreaux <moreaux.antoine@gmail.com>

packages/twenty-front/src/modules/object-metadata/hooks/__mocks__/useCreateOneRelationMetadataItem.ts

@@ -1,8 +1,10 @@
 import { gql } from '@apollo/client';
 
 export const query = gql`
-  mutation CreateOneRelationMetadata($input: CreateOneRelationInput!) {
-    createOneRelation(input: $input) {
+  mutation CreateOneRelationMetadataItem(
+    $input: CreateOneRelationMetadataInput!
+  ) {
+    createOneRelationMetadata(input: $input) {
       id
       relationType
       fromObjectMetadataId
@@ -17,7 +19,7 @@ export const query = gql`
 
 export const variables = {
   input: {
-    relation: {
+    relationMetadata: {
       fromDescription: null,
       fromIcon: undefined,
       fromLabel: 'label',

packages/twenty-front/src/modules/object-metadata/hooks/__mocks__/useFindManyObjectMetadataItems.ts

@@ -2,7 +2,7 @@ import { gql } from '@apollo/client';
 import { mockedStandardObjectMetadataQueryResult } from '~/testing/mock-data/generated/mock-metadata-query-result';
 
 export const query = gql`
-  query ObjectMetadataItems($objectFilter: objectFilter, $fieldFilter: fieldFilter) {
+  query ObjectMetadataItems($objectFilter: ObjectFilter, $fieldFilter: FieldFilter) {
     objects(paging: {first: 1000}, filter: $objectFilter) {
       edges {
         node {