Packet handling fixes

[cocosolos]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

• Use a copy of the PacketList in case there are any issues while sending.
• Pop packets from PacketList only after finished sending.
• Fix an issue with players using the wrong update packet.

Related issues: #6842, #6829, #6778, #6746

Steps to test these changes

Zone in to Ru'Lude and see stuff. Zone in near another player and see eachother. Watch as things disappear when they get too far.

[cocosolos]

I think this fixes all the linked issues, though I'm too tired to thoroughly test right now. It looks like #6751 is the source of the player update issues. CZoneEntities::TryAddToNearbySpawnLists had PCs using updateEntityPacket instead of updateCharPacket (I was actually working on combining these 2 and doing some renaming when this issue came up, will have a followup maybe tomorrow for that + some other stuff).

NPCs load in Ru'Lude, players are visible when using !goto or zoning, NPCs disappear when they go out of range. IDK if I'm missing anything but seems alright.

[zach2good]

This also seems to now finish the job of my fix for "other players won't be visible if I zone next to them" due to the TryInsertIntoSpawnList call now doing what it's meant to