Factor out a type from InjectionMethods that stores TypeMirrors instead of MethodSpec/TypeNames

This will help fix a bug in AOT where we need to insert a cast conditionally if a type is assignable or not

RELNOTES=n/a

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=226522358
diff --git a/java/dagger/internal/codegen/MembersInjectionMethods.java b/java/dagger/internal/codegen/MembersInjectionMethods.java
index 34c6179..bef30fc 100644
--- a/java/dagger/internal/codegen/MembersInjectionMethods.java
+++ b/java/dagger/internal/codegen/MembersInjectionMethods.java
@@ -104,7 +104,8 @@
             request ->
                 bindingExpressions
                     .getDependencyArgumentExpression(request, componentImplementation.name())
-                    .codeBlock()));
+                    .codeBlock(),
+            elements));
     methodBuilder.addStatement("return $L", instance);
 
     MethodSpec method = methodBuilder.build();