fix(build): Remove ambiguity in service method call (#327)

When calling methods on Arc<MyService> where the method is also defined on Arc (e.g. drop and clone), calling inner.#method_ident(request) will actually attempt to call the Arc method instead of the method on the service, resulting in a compile error. This change removes the ambiguity by dereferencing the inner Arc.

tests/ambiguous_methods/src/main.rs

@@ -0,0 +1,8 @@
+#[macro_use]
+extern crate tonic;
+
+tonic::include_proto!("ambiguous_methods");
+
+fn main() {
+    println!("Hello, world!");
+}