[PORT] Extend 'getProperty' builtin function to support accessing top memory.

[tomlm]

Port this change from botbuilder-dotnet/master branch:
microsoft/botbuilder-dotnet#4176

Fixes #4029
Originally, getProperty accepts two parameters, the first parameter is an instance, and the second parameter is the property name which user wants to access the value from. In this mode, the user can not access the top-level memory from dynamic/special string property.

After this change, getProperty accepts only one parameter, that presents the root property from the memory.

Example:
Scope is :

{
"a:b": "value"
}

getProperty('a:b') would get string "value",

Changed projects

• AdaptiveExpressions
• AdaptiveExpressions.Tests