[WTF] Use CompactPtr in AtomStringTable if it is more efficient

[WTF] Use CompactPtr in AtomStringTable if it is more efficient
https://bugs.webkit.org/show_bug.cgi?id=241883

Reviewed by Darin Adler.

1. We add HashTable support for CompactPtr. Correctly setting up HashTraits and Hashers so that we can have HashSet<CompactPtr<T>>.
2. Use CompactPtr in AtomStringTable if it is more efficient than PackedPtr<StringImpl>. Typically, this means we are in iOS.

* Source/WTF/wtf/CompactPtr.h:
(WTF::CompactPtr::CompactPtr):
(WTF::CompactPtr::encode):
(WTF::CompactPtr::decode):
(WTF::CompactPtr::isHashTableDeletedValue const):
(WTF::CompactPtrTraits::hashTableDeletedValue):
(WTF::CompactPtrTraits::isHashTableDeletedValue):
* Source/WTF/wtf/Forward.h:
* Source/WTF/wtf/HashTraits.h:
(WTF::HashTraits<CompactPtr<P>>::emptyValue):
(WTF::HashTraits<CompactPtr<P>>::isEmptyValue):
(WTF::HashTraits<CompactPtr<P>>::peek):
* Source/WTF/wtf/text/AtomStringImpl.cpp:
(WTF::UCharBufferTranslator::equal):
(WTF::UCharBufferTranslator::translate):
(WTF::HashAndUTF8CharactersTranslator::equal):
(WTF::HashAndUTF8CharactersTranslator::translate):
(WTF::SubstringTranslator::translate):
(WTF::SubstringTranslator8::equal):
(WTF::SubstringTranslator16::equal):
(WTF::LCharBufferTranslator::equal):
(WTF::LCharBufferTranslator::translate):
(WTF::BufferFromStaticDataTranslator::equal):
(WTF::BufferFromStaticDataTranslator::translate):
* Source/WTF/wtf/text/AtomStringTable.h:
* Tools/TestWebKitAPI/Tests/WTF/CompactPtr.cpp:
(TestWebKitAPI::TEST):

link: https://commits.webkit.org/251776@main
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@295771 268f45cc-cd09-0410-ab3c-d52691b4dbfc