Cleanup HalInterfaces.h

Prior to this CL, HalInterfaces.h polluted the global namespace through
the "using" declarations. This CL creates a new ::android::nn::hal
namespace and places the names there instead.

This CL also changes the namespace of the Callback objects from
::android::hardware::neuralnetworks::V1_2::implementation to
::android::nn to be consistent with the other parts of frameworks/ml/nn.

Fixes: 72880287
Test: mma
Change-Id: I399ad32f5c541a493429c6fa8e192169a903ea9f
Merged-In: I399ad32f5c541a493429c6fa8e192169a903ea9f
(cherry picked from commit 19af9d2d509621c0b07fb5a0f59abd0adb9de468)
diff --git a/common/OperationsUtils.cpp b/common/OperationsUtils.cpp
index e128afb..9219ddd 100644
--- a/common/OperationsUtils.cpp
+++ b/common/OperationsUtils.cpp
@@ -27,6 +27,8 @@
 
 namespace {
 
+using namespace hal;
+
 bool validateOperandTypes(const std::vector<OperandType>& expectedTypes, const char* tag,
                           uint32_t operandCount,
                           std::function<OperandType(uint32_t)> getOperandType) {