If the method name is generated from the request type, there is a
possibility of a clash if two methods take the same request type. For
example, if two unique methods take the request type
"CreateRoleRequest", both methods will be generated with the method name
"create_role", which causes generation to fail with an exception.
This commit resolves that issue by first generating a method name from
the request type of each method, and keeping track of which names are
duplicates. For methods that will generate a duplicate name from the
request type, the name is generated from the method ID instead (the
resulting name is guaranteed to be unique).
Sai Cheemalapati
Steven Bazyl