Update the bicep extension used in the dev container (#7969)

# Description

Updated the Bicep VS Code extension in the dev container to use the
current version of the extension instead of the previous Radius Bicep
extension.

## Type of change

- This pull request is a minor refactor, code cleanup, test improvement,
or other maintenance task and doesn't change the functionality of Radius
(issue link optional).

Fixes: N/A

Signed-off-by: Brooke Hamilton <[email protected]>

Author: brooke-hamilton

.devcontainer/contributor/devcontainer.json

@@ -34,7 +34,7 @@
                 "golang.go",
                 "ms-python.python",
                 "ms-python.vscode-pylance",
-                "ms-azuretools.rad-vscode-bicep",
+                "ms-azuretools.vscode-bicep",
                 "ms-kubernetes-tools.vscode-kubernetes-tools",
                 "ms-azuretools.vscode-dapr",
                 "ms-vscode.makefile-tools"