Use std::unordered_map for mTagToTypeMap

In the profile we notice that  SortedVectorImpl::_indexOrderOf is
almost 1.6% which is quite high considering it is an access to
a container. We make mTagToNameMap as a std::unordered_map
to store the Tag and the types. The accesses would be in constant time.

This change removes this from the profile and give ~10% improvement.

Bug: 72526772
Change-Id: Iffd244febd093bdfec9fe4d5e846a0e59c0ecdce