Fix page layout widget tab moves (#20915)

Fixes widget moves between page layout tabs by making pageLayoutTabId
part of the flat-entity diff, so the save mutation no longer silently
drops the new tab assignment.

https://discord.com/channels/1130383047699738754/1508737039128985680

packages/twenty-server/src/engine/metadata-modules/flat-entity/constant/__tests__/__snapshots__/all-universal-flat-entity-properties-to-compare-and-stringify.constant.spec.ts.snap

@@ -214,6 +214,7 @@ exports[`ALL_UNIVERSAL_FLAT_ENTITY_PROPERTIES_TO_COMPARE_AND_STRINGIFY should ma
       "position",
       "universalConfiguration",
       "deletedAt",
+      "pageLayoutTabUniversalIdentifier",
       "conditionalDisplay",
       "conditionalAvailabilityExpression",
       "isActive",

packages/twenty-server/src/engine/metadata-modules/flat-entity/constant/all-entity-properties-configuration-by-metadata-name.constant.ts

@@ -930,7 +930,7 @@ export const ALL_ENTITY_PROPERTIES_CONFIGURATION_BY_METADATA_NAME = {
       universalProperty: undefined,
     },
     pageLayoutTabId: {
-      toCompare: false,
+      toCompare: true,
       toStringify: false,
       universalProperty: 'pageLayoutTabUniversalIdentifier',
       isOverridable: true,