Allow the user to specify inputs for .devcontainer.json

It would be nice to allow ${inputs:XXXX} format in .devcontainer.json similar to how it works in launch.json.

Here is an example in .devcontainer.json which doesn't currently work but would be nice to have

{
        "name": "Code Build Environment",
        "dockerFile": "/usr/share/dpkg-buildenv/Dockerfile",
        "build": {
                "args": {
                        "DISTRIBUTION" : "${inputs:distribution}"
                }
        },
	"inputs": [
		{
		  "id": "distribution",
		  "type":"promptString",
		  "description": "which base os to use",
		  "default": "debian:12"
		}
	],
}

Here is an example that does work in launch.json

{
	"configurations": [
       {
	 "name": "Attach to running <my_program>",
	 "type": "cppdbg",
	 "request": "launch",
	 "program": "${workspaceRoot}/build/src/<my_program>",
	 "miDebuggerServerAddress": "${input:remote_ip_address}:2345",
	 "cwd": "${workspaceRoot}",
       }
	],
	"inputs": [
       {
	 "id": "remote_ip_address",
	 "type":"promptString",
	 "description": "Management IP address of remote machine to debug.",
	 "default": "<management_ip_address>", 
       },
	]
      }

### Tasks