export some builtin traits,

brightness conversion fails for invalid values,

macros for wrapping attrs

src/brightness.rs

@@ -1,3 +1,4 @@
+use crate::errors::ServicePointError;
 use crate::UniffiCustomTypeConverter;
 use servicepoint::Brightness;
 
@@ -10,7 +11,8 @@ impl UniffiCustomTypeConverter for Brightness {
     where
         Self: Sized,
     {
-        Ok(Brightness::saturating_from(val))
+        Ok(Brightness::try_from(val)
+            .map_err(|value| ServicePointError::InvalidBrightness { value })?)
     }
 
     fn from_custom(obj: Self) -> Self::Builtin {