Add semantic model to SyntaxTree visualizer

[hootanht]

Fixes #229

Add Semantic Model to SyntaxTree visualizer.

• CodeController.cs

  • Add a new endpoint to retrieve the semantic model for a given script.
  • Use ICodeAnalysisService to get the semantic model.
  • Return the semantic model as a JSON result.

• CodeAnalysisService.cs

  • Add a new method GetSemanticModel to retrieve the semantic model for a given code.
  • Use CSharpCompilation to get the semantic model.

• ICodeAnalysisService.cs

  • Add a new method GetSemanticModel to the interface.

• syntax-tree-view.ts

  • Add a new method to load the semantic model.
  • Update the UI to display semantic model information.
  • Cache the semantic model along with the syntax tree.

• syntax-tree-view.html

  • Add new elements to display semantic model information.