Fix C# examples in documentation

- Fix documentation after C# renames.
- Add missing `partial` in C# class declarations.
- Change `delta` parameter type to `double` in C#.
- Ensure parameters match base declaration.
- Use `$` string interpolation in C#.
- Fix invalid or outdated C# code.
- Changed some examples to follow our style guide more closely.

doc/classes/EditorTranslationParserPlugin.xml

@@ -27,27 +27,25 @@
 		[/gdscript]
 		[csharp]
 		using Godot;
-		using System;
 
 		[Tool]
-		public class CustomParser : EditorTranslationParserPlugin
+		public partial class CustomParser : EditorTranslationParserPlugin
 		{
-		    public override void ParseFile(string path, Godot.Collections.Array msgids, Godot.Collections.Array msgidsContextPlural)
+		    public override void _ParseFile(string path, Godot.Collections.Array<string> msgids, Godot.Collections.Array<Godot.Collections.Array> msgidsContextPlural)
 		    {
-		        var file = new File();
-		        file.Open(path, File.ModeFlags.Read);
+		        using var file = FileAccess.Open(path, FileAccess.ModeFlags.Read);
 		        string text = file.GetAsText();
-		        string[] splitStrs = text.Split(",", false);
-		        foreach (var s in splitStrs)
+		        string[] splitStrs = text.Split(",", allowEmpty: false);
+		        foreach (string s in splitStrs)
 		        {
 		            msgids.Add(s);
-		            //GD.Print("Extracted string: " + s)
+		            //GD.Print($"Extracted string: {s}");
 		        }
 		    }
 
-		    public override Godot.Collections.Array GetRecognizedExtensions()
+		    public override string[] _GetRecognizedExtensions()
 		    {
-		        return new Godot.Collections.Array{"csv"};
+		        return new string[] { "csv" };
 		    }
 		}
 		[/csharp]
@@ -84,16 +82,16 @@
 		    return ["gd"]
 		[/gdscript]
 		[csharp]
-		public override void ParseFile(string path, Godot.Collections.Array msgids, Godot.Collections.Array msgidsContextPlural)
+		public override void _ParseFile(string path, Godot.Collections.Array<string> msgids, Godot.Collections.Array<Godot.Collections.Array> msgidsContextPlural)
 		{
 		    var res = ResourceLoader.Load<Script>(path, "Script");
 		    string text = res.SourceCode;
 		    // Parsing logic.
 		}
 
-		public override Godot.Collections.Array GetRecognizedExtensions()
+		public override string[] _GetRecognizedExtensions()
 		{
-		    return new Godot.Collections.Array{"gd"};
+		    return new string[] { "gd" };
 		}
 		[/csharp]
 		[/codeblocks]