Updating/work-with this template for GHA and Azd Devcontainer feature.

[zedy-wj]

We are updating this template to support new features in Github Action and Azd Devcontainer.

1. For the Github Action feature: We will remove two lines of code on container image and add GHA code after checkout step in the .github/workflow/azure-dev.yml file. (Shown as below)

2. For the Azd Devcontainer feature: We will remove dockerfile in .devcontainer folder and add the following code in devcontainer.json file,

"ghcr.io/azure/azure-dev/azd:latest": {}

and image also need to be add instead of build. Such as:

@rajeshkamal5050 , @sabbour for notification.