Workspace migration v2 Metadadata runner object and field (#13377)

# Introduction
Created the runner metadata for the field and object
We should keep in mind that any runner handler will only iterate over an
atomic instance of entity ( object field index etc )
Never triggerring any side effect or whats over

In this way we will need to implement a deferred transaction, as for
when we create a relation we will inject to the first created field of
both the `relationTargetFieldMetadataId` deterministically computed
before its own creation
This would result in pg constraint brokage if not deferred

## Updates
- We decided gather create_fields under the create_object as they will
be building within the same sql query. This will ease both generation
and computation and avoid disassembling to reassemble afterwards
- Refactored FlatFieldMetadata to handle relation typing with flat
occurences
```ts
  runCreateFieldSchemaMigration = async ({
    action,
    queryRunner,
  }: WorkspaceMigrationActionRunnerArgs<CreateFieldAction>) => {
    if (isFlatFieldMetadataEntityOfType(action.flatFieldMetadata, FieldMetadataType.RELATION)) {
      action.flatFieldMetadata.flatRelationTargetObjectMetadata
    }else {
      action.flatFieldMetadata.flatRelationTargetObjectMetadata // tsc-error never
    }
    return;
  };
```

## TODO
- ~~Discuss action signature with @Weiko in order to anticipate `schema`
runner needed grain~~
- ~~Refactor the object actions to contain picked `flatObjectMetadata`~~
- Implem index service

packages/twenty-server/src/engine/workspace-manager/workspace-migration-v2/utils/is-flat-field-metadata-of-type.util.ts

@@ -0,0 +1,13 @@
+import { FieldMetadataType } from 'twenty-shared/types';
+
+import { FlatFieldMetadata } from 'src/engine/workspace-manager/workspace-migration-v2/types/flat-field-metadata';
+
+export function isFlatFieldMetadataEntityOfType<
+  Field extends FlatFieldMetadata<FieldMetadataType>,
+  Type extends FieldMetadataType,
+>(
+  fieldMetadata: Pick<Field, 'type'>,
+  type: Type,
+): fieldMetadata is Field & FlatFieldMetadata<Type> {
+  return fieldMetadata.type === type;
+}