Request: Add method to PluginSdk, GetAllVars

[tenholde]

While we can create and retrieve HS Global Vars, there is no way to retrieve a list of all currently defined Vars.

Need something like GetAllVars that would return a List (of String) that contains the name of all curretnly defined Global Variables.

Thank you for your consideration

[spudwebb]

Tracked as PSDK-307