[Requires "warm" cache flush (no immediate downtime before flush)] Migrate viewGroup.fieldMetadataId -> view.mainGroupByFieldMetadataId (1/3) (#16206)

In this PR (1/3)
- introduce view.mainGroupByFieldMetadataId as the new reference
determining which fieldMetadataId is used in a grouped view, in order to
deprecate viewGroup.fieldMetadataId which creates inconsistencies.
view.mainGroupByFieldMetadataId is now filled at every view creation,
though not in use yet.
- Introduce a command to backfill view.mainGroupByFieldMetadataId for
existing views + delete all viewGroup.fieldMetadataId with a
fieldMetadataId that is not view.mainGroupByFieldMetadataId. (It should
concern 37 active workspaces)
- Temporarily disable the option to change a grouped view's
fieldMetadataId as for now it creates inconsistencies. This feature can
be reintroduced when we have done the full migration.

In a next PR
- (2/3) use view.mainGroupByFieldMetadataId instead of
viewGroup.fieldMetadataId. In FE we may keep viewGroup.fieldMetadataId
as a state (TBD). View groups will now be created / deleted as a side
effect of view's mainGroupByFieldMetadataId update.
- (3/3) remove viewGroup.fieldMetadataId

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/engine/metadata-modules/flat-view/utils/from-create-view-input-to-flat-view-to-create.util.ts

@@ -44,6 +44,8 @@ export const fromCreateViewInputToFlatViewToCreate = ({
     kanbanAggregateOperation: createViewInput.kanbanAggregateOperation ?? null,
     kanbanAggregateOperationFieldMetadataId:
       createViewInput.kanbanAggregateOperationFieldMetadataId ?? null,
+    mainGroupByFieldMetadataId:
+      createViewInput.mainGroupByFieldMetadataId ?? null,
     key: createViewInput.key ?? null,
     openRecordIn: createViewInput.openRecordIn ?? ViewOpenRecordIn.SIDE_PANEL,
     position: createViewInput.position ?? 0,