perf: use a ref inside the new array and reduce code size

... from my previous attempt, still a bit larger than the original.

             | Original | Previous Commit   | Current Commit    |
-------------|----------|-------------------|-------------------|
Status       | crash    | works             | works             |
Fields       | 2046     | 3 (-2043)         | 4 (+1)            |
Locals       | 2048     | 2048              | 2049 (+1)         |
IL Code Size | 179,715  | 215,349 (+35,634) | 183,429 (-31,920) |

Also generate code that is easier to read.

src/SourceGenerators/Uno.UI.SourceGenerators/BindableTypeProviders/BindableTypeProvidersGenerationTask.cs

@@ -594,38 +594,41 @@ private bool IsOverride(IMethodSymbol? methodDefinition)
 			private void GenerateTypeTable(IndentedStringBuilder writer)
 			{
 				var types = _typeMap.Where(k => !k.Key.IsGenericType);
-				writer.AppendLineIndented($"private global::Uno.UI.DataBinding.IBindableType[] _bindableTypes = new global::Uno.UI.DataBinding.IBindableType[{types.Count()}];");
+				writer.AppendLineIndented($"private readonly global::Uno.UI.DataBinding.IBindableType[] _bindableTypes = new global::Uno.UI.DataBinding.IBindableType[{types.Count()}];");
+				writer.AppendLineIndented($"private static global::Uno.UI.DataBinding.IBindableType _null;");
 
 				using (writer.BlockInvariant("public global::Uno.UI.DataBinding.IBindableType GetBindableTypeByFullName(string fullName)"))
 				{
+					writer.AppendLineIndented("ref global::Uno.UI.DataBinding.IBindableType element = ref _null;");
 					using (writer.BlockInvariant(@"switch(fullName)"))
 					{
 						foreach (var type in types)
 						{
 							_cancellationToken.ThrowIfCancellationRequested();
 
-							var typeIndexString = $"{type.Value.Index:000}";
+							var typeIndex = type.Value.Index;
 
-							writer.AppendLineIndented($"case \"{type.Key}\":");
-							using (writer.BlockInvariant($"if(_bindableTypes[{typeIndexString}] == null)"))
+							using (writer.BlockInvariant($"case \"{type.Key}\":"))
 							{
-								if (_xamlResourcesTrimming && type.Key.GetAllInterfaces().Any(i => SymbolEqualityComparer.Default.Equals(i, _dependencyObjectSymbol)))
+								writer.AppendLineIndented($"element = ref _bindableTypes[{typeIndex}];");
+								using (writer.BlockInvariant("if(element == null)"))
 								{
-									var linkerHintsClassName = LinkerHintsHelpers.GetLinkerHintsClassName(_defaultNamespace);
-									var safeTypeName = LinkerHintsHelpers.GetPropertyAvailableName(type.Key.GetFullMetadataName());
+									if (_xamlResourcesTrimming && type.Key.GetAllInterfaces().Any(i => SymbolEqualityComparer.Default.Equals(i, _dependencyObjectSymbol)))
+									{
+										var linkerHintsClassName = LinkerHintsHelpers.GetLinkerHintsClassName(_defaultNamespace);
+										var safeTypeName = LinkerHintsHelpers.GetPropertyAvailableName(type.Key.GetFullMetadataName());
+
+										writer.AppendLineIndented($"if(global::{linkerHintsClassName}.{safeTypeName})");
+									}
 
-									writer.AppendLineIndented($"if(global::{linkerHintsClassName}.{safeTypeName})");
+									writer.AppendLineIndented($"element = MetadataBuilder_{typeIndex:000}.Build();");
 								}
 
-								writer.AppendLineIndented($"_bindableTypes[{typeIndexString}] = MetadataBuilder_{typeIndexString}.Build();");
+								writer.AppendLineIndented("break;");
 							}
-
-							writer.AppendLineIndented($"return _bindableTypes[{typeIndexString}];");
 						}
-
-						writer.AppendLineIndented("default:");
-						writer.AppendLineIndented(@"return null;");
 					}
+					writer.AppendLineIndented("return element;");
 				}
 
 				using (writer.BlockInvariant("public global::Uno.UI.DataBinding.IBindableType GetBindableTypeByType(Type type)"))