aoc2024: Implement day23 solution

I'm not proud of my implementation to last 2 days, but they work in a
reasonable time. I might optimize them later...

Problem is largely with my hash structures. Preallocating a lot of
elements before running day22 makes it run in less than half of the
current time.

userspace/aoc2024/CMakeLists.txt

@@ -21,6 +21,7 @@ set(AOC2024_PROJECTS
 	day20
 	day21
 	day22
+	day23
 	full
 )