Expose a method getter api so

Summary:
Module currently cannot compose with apis that operate directly on module.

Exposing the method directly so that module can compose with these lower level apis. The first practical use case of this is io manager for llms.

Differential Revision: D77248983

Author: JacobSzwejbka

extension/module/module.cpp

@@ -228,6 +228,16 @@ runtime::Error Module::load_method(
   return runtime::Error::Ok;
 }
 
+ET_NODISCARD inline runtime::Result<Method*> Module::method(
+  const std::string& method_name) {
+ET_CHECK_OR_RETURN_ERROR(
+    methods_.count(method_name) > 0,
+    InvalidArgument,
+    "no such method in program: %s",
+    method_name.c_str());
+return methods_[method_name].method.get();
+}
+
 runtime::Result<MethodMeta> Module::method_meta(
     const std::string& method_name) {
   ET_CHECK_OK_OR_RETURN_ERROR(load());

extension/module/module.h

@@ -194,6 +194,18 @@ class Module {
     return load_method(method_name, nullptr, event_tracer);
   }
 
+  /**
+   * Get a method by it's name. Not recommended to use this method directly as an end user. 
+   * It's exposed to allow for composability of module in apis that operate on method. 
+   *
+   * @param[in] method_name The name of the method to get.
+   *
+   * @returns A Result object containing either a pointer to the requested
+   *          method or an error to indicate failure.
+   */
+   ET_NODISCARD inline runtime::Result<Method*> method(
+    const std::string& method_name);
+
   /**
    * Load the 'forward' method from the program and set up memory management if
    * needed. The loaded method is cached to reuse the next time it's executed.