[PORT] Fix anonymous template name conflict

[tomlm]

Port this change from botbuilder-dotnet/master branch:
microsoft/botbuilder-dotnet#4329

Fixes #4328

Description

Currently, LG uses __temp__ as the template id when evaluating inline text with EvaluateText method.
Later, the expandText function was introduced, which would use the evaluateText to achieve the result. So, there would exist two __temp__ templates.

Specific Changes

Assign a random ID for template name when evaluating an inline text to support the nested inline text evaluation.

Changed projects

• Microsoft.Bot.Builder.LanguageGeneration
• Microsoft.Bot.Builder.LanguageGeneration.Tests