Add support for inspecting CallingScriptHash, EntryScriptHash, CurrentScriptHash

[ixje]

In the screenshot above I'm hovering over the entry_script_hash (line 108 ). It shows no value (the same happens for calling_script_hash). These values also are not present in the variables pane on the left side, so there is no means of knowing what the values are. Given that this also does not work on a C# contract it is believed this is support is missing on the debugger side.