Support namespace style component interface function names

[TwitchBronBron]

<interface>
  <function name="Namespace.FunctionName" />
  <field id="width" type="float" onchange="Namespace.FunctionName" />
</interface>

This should be supported. The validator should properly find these namespaced functions, and the transpiler should rewrite to Namespace_FunctionName.

For legacy reasons, we need to also still support Namespace_FunctionName as well.

Another situation we'll need to address is for completions and validations, we shouldn't allow Namespace.FunctionName when the project is pure brightscript. (we need to work this out)