Update on-create.sh for Bicep extension installation

[jasonviviano]

What content needs to be created or modified?

The on-create.sh for the devcontainer is currently using an outdated curl call to get.radapp for the Bicep extension. This needs to be modified with a more updated version that uses either GitHub or the VS Code Marketplace.

Describe the solution you'd like

A GHCR pull or a pull from the VS Code Marketplace.

Where should the new material be placed?

docs/.devcontainer/on-create.sh

Line 19 in c9c773c

 curl https://get.radapp.dev/tools/vscode-extensibility/$RADIUS_VERSION/rad-vscode-bicep.vsix --output /tmp/rad-vscode-bicep.vsix 

The associated pull request from the Radius code repo, if applicable

Additional context

Related to radius-project/radius#7295

AB#11438

[jasonviviano]

Closing as complete