[Feature] 支持校验docker images是否可用

**Feature Category**
- [ ] Sandbox
- [ ] Actions
- [ ] Deployments
- [ ] SDK & API
- [x] Envhub
- [ ] CLI 
- [ ] Performance & Optimization
- [ ] Documentation & Examples

**Problem Statement**
dockerhub偶发docker pull失败，需要支持元数据可用性。

**Proposed Solution**

**Detailed Feature Description**


