Convert tf.FusedBatchNorm into tfl primary math ops

* Added TF::FusedBatchNormOp
* Validated TF::FusedBatchNormOp's operands
* Added converter from tf.FusedBatchNorm to tfl math ops

In the converter, we additionally check that the 'is_training'
attribute in tf.FusedBatchNorm is false and the last 4 outputs
are all not used (true for inference). These requirements do
not exist in the original TOCO source code, which just silently
ignores the last 4 outputs.

PiperOrigin-RevId: 223027333

mlir/include/mlir/IR/OpDefinition.h

@@ -537,6 +537,8 @@ public:
   template <typename ConcreteType>
   class Impl : public TraitBase<ConcreteType, NResults<N>::Impl> {
   public:
+    static unsigned getNumResults() { return N; }
+
     const SSAValue *getResult(unsigned i) const {
       return this->getOperation()->getResult(i);
     }