feat: Show comprehensive error when an RPC is not found in a stale schema cache (#1841)

* Add 300 response for overloaded functions with same argument names but different types
* Add Path type to handle validations and errors before defining the Target

test/fixtures/schema.sql

@@ -1305,6 +1305,27 @@ create or replace function test.overloaded_html_form(a text, b text, c text) ret
 select a || b || c
 $$ language sql;
 
+create or replace function test.overloaded_same_args(arg integer) returns json as $$
+select json_build_object(
+    'type', pg_typeof(arg),
+    'value', arg
+  );
+$$ language sql;
+
+create or replace function test.overloaded_same_args(arg xml) returns json as $$
+select json_build_object(
+    'type', pg_typeof(arg),
+    'value', arg
+  );
+$$ language sql;
+
+create or replace function test.overloaded_same_args(arg text, num integer default 0) returns json as $$
+select json_build_object(
+    'type', pg_typeof(arg),
+    'value', arg
+  );
+$$ language sql;
+
 create table test.leak(
   id serial primary key,
   blob bytea