Consider packaging `dnx` with the .NET Runtime

The [new `dnx` features](https://github.com/dotnet/core/blob/main/release-notes/10.0/preview/preview6/sdk.md#the-new-dnx-tool-execution-script) are awesome. They make it really convenient to run .NET tools. However, they require the entire .NET SDK to run. It would be even more convenient if `dnx` was usable with only the .NET Runtime installed.

For example, I would like to run a tool using `dnx` in a .NET Runtime container image. However, I need to use the entire SDK image.

For comparison, the size of the .NET 10 Preview 6 linux-x64 SDK is **~230 MB**, whereas the Runtime is just **~35 MB**. And `mcr.microsoft.com/dotnet/sdk:10.0-preview` is ~332 MB while `mcr.microsoft.com/dotnet/runtime:10.0-preview` is ~83 MB.