AK: Add an ArbitrarySizedEnum template

This is an enum-like type that works with arbitrary sized storage > u64,
which is the limit for a regular enum class - which limits it to 64
members when needing bit field behavior.

Co-authored-by: Ali Mohammad Pur <mpfard@serenityos.org>

Tests/AK/CMakeLists.txt

@@ -2,6 +2,7 @@ set(AK_TEST_SOURCES
     TestFixedPoint.cpp
     TestAllOf.cpp
     TestAnyOf.cpp
+    TestArbitrarySizedEnum.cpp
     TestArray.cpp
     TestAtomic.cpp
     TestBadge.cpp