improvement(codebase): centralize test mocks, extract @sim/utils, rem… #14948

Job	Run time
Detect Version	4s
Test and Build / Test and Build	44s
Check Docs Changes	-1s
Build ARM64 (GHCR Only)	0s
Build Dev ECR	0s
Migrate Dev DB	0s
Build AMD64 (./docker/realtime.Dockerfile, ghcr.io/simstudioai/realtime, ECR_REALTIME)	2m 51s
Build AMD64 (./docker/app.Dockerfile, ghcr.io/simstudioai/simstudio, ECR_APP)	5m 31s
Build AMD64 (./docker/db.Dockerfile, ghcr.io/simstudioai/migrations, ECR_MIGRATIONS)	1m 43s
Create GHCR Manifests	0s
Process Docs	0s
Create GitHub Release	0s
	10m 52s

Provide feedback