Implement macOS accessibility value setter (#20262)

native/Avalonia.Native/src/OSX/automation.mm

@@ -216,6 +216,22 @@
     return [super accessibilityValue];
 }
 
+- (void)setAccessibilityValue:(id)newValue
+{
+    if (_peer->IsValueProvider())
+    {
+        if (newValue == nil)
+            _peer->ValueProvider_SetValue(nil);
+        else if ([newValue isKindOfClass:[NSString class]])
+            _peer->ValueProvider_SetValue([(NSString*)newValue UTF8String]);
+    }
+    else if (_peer->IsRangeValueProvider())
+    {
+        if ([newValue isKindOfClass:[NSNumber class]])
+            _peer->RangeValueProvider_SetValue([(NSNumber*)newValue doubleValue]);
+    }
+}
+
 - (id)accessibilityMinValue
 {
     if (_peer->IsRangeValueProvider())

src/Avalonia.Controls/Automation/Provider/IRangeValueProvider.cs

@@ -127,7 +127,7 @@
         ///   <item>
         ///     <term>macOS</term>
         ///     <description>
-        ///       <c>NSAccessibilityProtocol.setAccessibilityValue</c> (not implemented)
+        ///       <c>NSAccessibilityProtocol.setAccessibilityValue</c>
         ///     </description>
         ///   </item>
         /// </list>

src/Avalonia.Controls/Automation/Provider/IValueProvider.cs

@@ -57,7 +57,7 @@
         ///   <item>
         ///     <term>macOS</term>
         ///     <description>
-        ///       <c>NSAccessibilityProtocol.setAccessibilityValue</c> (not implemented)
+        ///       <c>NSAccessibilityProtocol.setAccessibilityValue</c>
         ///     </description>
         ///   </item>
         /// </list>

src/Avalonia.Native/avn.idl

@@ -1317,7 +1317,7 @@ interface IAvnAutomationPeer : IUnknown
      
      bool IsValueProvider();
      IAvnString* ValueProvider_GetValue();
-     void ValueProvider_SetValue(char* value);
+     void ValueProvider_SetValue([const] char* value);
 
      IAvnString* GetHelpText();