Switch the GameDatabase from using a pxDictionary to a std::unordered_map.

Both implementations are about the same, which is hard to measure since we are limited in speed due to the hashing function.

Both implementations averaged ~220ms to load the full game database on my workstation.
Remove the pxDictionary class since it is no longer needed.
This was only used by the game database, which has now been changed to an unordered_map
Also remove UnicodeDictionary.

This class isn't used anywhere and we should promote usage of std::unordered_map instead of this class
Remove usages of HashTools::Dictionary/HashMap

Replace these usages with unordered_map since they are just as quick
Remove HashTools::HashMap/SpecializedHashMap

These are no longer used. Wipe them out.
Remove HashTools::HashSet.

This is no longer used.
Remove HashTools::IHashable/CommonComparisonClass

These are no longer used.