It was a very outdated code.
Also, I can't belive we've used it like this, its horrible.. Heap allocating and copying vectors, and maps for every packet?
This PR fixes it all! At once. (Coudnt really break it into more PRs).

Features:

• Added static BroadcastIf - Send the packet only to a player for which predicate is true
• BroadcastJoinedIf - A member function that uses the internally stored and optimized m_JoinedByBitStreamVer for BroadcastIf
• The above mentioned function can be used like as a base for other existing functions, for example: BroadcastJoinedDimension (I've refactored all of them to use BroadcastJoinedIf)
• The former 2 give a pretty good performance boost. Not tested, but it would make sense, especially on servers where there are a lot of packets sent / frame. (No heap allocs anymore, and sorts, so :D)
• Refactored the code to c++17 standards - Now its even more readable
• Added 2 todos!! Maybe even more!
• Added noexcept and const wherever possible
• Cleaned up old code related to the manager (eg.: Use GetAllPlayers() instead of IterBegin and IterEnd, and use IterateJoined where the old code used IterBegin and IterEnd and checked if the player is joined)
• Moved CSendList from CGame to its own file, because in the process of refactoring it ended up being quite big
• Added GetNetServerReliability and GetNetServerPriority to CPacket. These functions are wrappers and translator of GetFlags (They translate from our enum to raknet enums)

When reviewing

• See if the old codes logic matches the new one. Eg.: In commit bdbb722 see if I've missed a check we copy pasting code, or something. (I didnt)

@qaisjp Sorry for some fuckups in the commits, but coudn't properly select staged in vsc.
I've tried my best to make the commits atomic.