Command Line Namespace Option Consumes AZSL File Path

[santorac]

Run a command like "azslc.exe --namespace dx MyShader.azsl". It will report an error "input file could not be opened". If you step through in a debugger, you'll see that the namespace option thinks there are two namespaces: "dx" and "MyShader.azsl".

I suggest we change the data type for namespace to be a single string, instead of a list of strings, so it will stop when it hits a space. Then split the string on the "," character to support multiple namespaces.