Implement screen reader detection for everything but Android.

Android support is waiting on Godot 3.2.2 when the new plugin system lands.

Cargo.toml

@@ -10,3 +10,6 @@ crate-type = ["cdylib"]
 [dependencies]
 gdnative = "0.8"
 tts = { git = "https://gitlab.com/ndarilek/tts-rs" }
+
+[target.'cfg(windows)'.dependencies]
+tolk = "0.2"

TTS.gd

@@ -127,13 +127,27 @@ func get_is_rate_supported():
 
 var is_rate_supported setget , get_is_rate_supported
 
-func get_can_detect_screen_reader():
-    if OS.get_name() == "Windows":
+func _get_can_detect_screen_reader():
+    if Engine.has_singleton("AndroidTTS"):
         return true
-    else:
+    elif OS.has_feature('JavaScript'):
+        return false
+    elif tts != null:
+        return tts.can_detect_screen_reader
     return false
 
-var can_detect_screen_reader setget , get_can_detect_screen_reader
+var can_detect_screen_reader setget , _get_can_detect_screen_reader
+
+func _get_has_screen_reader():
+    if Engine.has_singleton("AndroidTTS"):
+        return tts.has_screen_reader()
+    elif OS.has_feature('JavaScript'):
+        return false
+    elif tts != null:
+        return tts.has_screen_reader
+    return false
+
+var has_screen_reader setget , _get_has_screen_reader
 
 func singular_or_plural(count, singular, plural):
     if count == 1:

src/lib.rs

@@ -79,6 +79,25 @@ impl TTS {
                 }
             })
             .done();
+        builder
+            .add_property("can_detect_screen_reader")
+            .with_getter(|_: &TTS, _| {
+                #[cfg(windows)]
+                return true;
+                return false;
+            })
+            .done();
+        builder
+            .add_property("has_screen_reader")
+            .with_getter(|_: &TTS, _| {
+                #[cfg(windows)]
+                {
+                    let tolk = tolk::Tolk::new();
+                    tolk.detect_screen_reader().is_some()
+                }
+                false
+            })
+            .done();
     }
 
     #[export]