feat(core): Export some entity utils from service helpers

`patchEntity` and `getEntityOrThrow` make it simpler to write resolvers / services in plugins.

packages/core/src/service/index.ts

@@ -1,5 +1,7 @@
 export * from './helpers/job-manager/job';
 export * from './helpers/utils/translate-entity';
+export * from './helpers/utils/patch-entity';
+export * from './helpers/utils/get-entity-or-throw';
 export * from './helpers/list-query-builder/list-query-builder';
 export * from './helpers/order-state-machine/order-state';
 export * from './helpers/payment-state-machine/payment-state';