Add blank sample with only implicit usings

Author: kzu

src/Demo/Hello.cs

@@ -0,0 +1,3 @@
+#:property ImplicitUsings=true
+
+Console.WriteLine("Hello, World!");

src/Demo/Mcp.cs

@@ -1,5 +1,6 @@
 #:property Title=LaTeX to Image MCP
 #:property Version=0.5.0
+#:property ImplicitUsings=true
 #:package [email protected]
 #:package [email protected].*
 #:package [email protected].*

src/Demo/Properties/launchSettings.json

@@ -5,6 +5,9 @@
     },
     "Mcp.cs": {
       "commandName": "Project"
+    },
+    "Hello.cs": {
+      "commandName": "Project"
     }
   }
 }