Fix various C# exceptions

- Replace `IndexOutOfRangeException` with `ArgumentOutOfRangeException`
- Replace `Exception` with a more specific exception
- Add the parameter name to argument exception
- Update documentation for methods that throw exceptions
- Use `StringBuilder` to build exception messages
- Ensure exception messages end with a period

modules/mono/editor/GodotTools/GodotTools.ProjectEditor/ProjectGenerator.cs

@@ -15,7 +15,7 @@ namespace GodotTools.ProjectEditor
         public static ProjectRootElement GenGameProject(string name)
         {
             if (name.Length == 0)
-                throw new ArgumentException("Project name is empty", nameof(name));
+                throw new ArgumentException("Project name is empty.", nameof(name));
 
             var root = ProjectRootElement.Create(NewProjectFileOptions.None);
 
@@ -37,7 +37,7 @@ namespace GodotTools.ProjectEditor
         public static string GenAndSaveGameProject(string dir, string name)
         {
             if (name.Length == 0)
-                throw new ArgumentException("Project name is empty", nameof(name));
+                throw new ArgumentException("Project name is empty.", nameof(name));
 
             string path = Path.Combine(dir, name + ".csproj");