[mlir] Improve FieldParser list container detection

The current detection logic will fail for containers with an overloaded
`push_back` member. This causes issues with types like `std::vector` and
`SmallVector<SomeNonTriviallyCopyableT>`, which have both
`push_back(const T&)` and `push_back(T&&)`.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D147101