[ECS] Support PlanPreview, LiveState, DriftDetection for ECS

[t-kikuc]

What would you like to be added:

Support 3 features below for ECS:

1. Plan Preview
2. Live State
3. Drift Detection

Note: I make this PR as epic because these features are closely connected and we need some common components in advance.

Why is this needed:

To support the real GitOps for ECS too.

Task List

• Diff() func (in piped)
  • cf. pkg/app/piped/platformprovider/cloudrun/diff.go
• [ECS] Support Plan Preview for ECS #4870
  • Prerequisites: Diff() is implemented
• [ECS] Implement LiveStateStore&Reporter for ECS #4905
• LiveState Graph (in web) (not in a hurry)
  • cf. cloudrun-state-view/index.tsx
• Drift Detection (in piped)
  • Prerequisites:
    • Diff() is implemented
    • LiveStateStore is implemented

cf. the features' dependency is like this: