refact: 将编译中各个阶段接口化 (#35)

Reviewed-on: PostGuard/Canon#35

Canon.Core/CodeGenerators/CCodeBuilder.cs

@@ -0,0 +1,22 @@
+using System.Text;
+
+namespace Canon.Core.CodeGenerators;
+
+/// <summary>
+/// 构建C语言代码
+/// </summary>
+public class CCodeBuilder
+{
+    private readonly StringBuilder _builder = new();
+
+    public void AddString(string code)
+    {
+        _builder.Append(code);
+    }
+
+
+    public string Build()
+    {
+        return _builder.ToString();
+    }
+}