new feature: devcontainer setup slow

### Feature Description

Devcontainer is supposed to be lightweight, which means it could be easily setup and tear down.
Opendal uses [post create commands](https://github.com/apache/opendal/blob/main/.devcontainer/post_create.sh) to install necessary dependencies.

It leads to a problem, post create commands are executed repeated every time devcontainer restarts.

### Problem and Solution

The better solution is to place heavy-loaded installation into docker file, which in turn leverages docker image cache to avoid re-installation.

### Additional Context

This is my setup at moonlink project:
- dockerfile contains all dependency installation: https://github.com/Mooncake-Labs/moonlink/blob/main/.devcontainer/Dockerfile
- post create setup command only include lightweight commands: https://github.com/Mooncake-Labs/moonlink/blob/main/.devcontainer/setup.sh

### Are you willing to contribute to the development of this feature?

- [ ] Yes, I am willing to contribute to the development of this feature.

Start with .devcontainer/post_create.sh to identify the dependency installation that runs on every restart. Compare the linked Moonlink Dockerfile and setup.sh for the intended split between image-build and post-create work. Done means heavy installation is cached in the Docker image and post-create commands remain lightweight, so restarting the devcontainer does not reinstall dependencies.

Written by the indexing model from the issue text.