feat(server): add DOES_PLAYER_EXIST native

this should replace the need to use GetPlayerPing and other natives which rely on implementation details

code/components/citizen-server-impl/src/PlayerScriptFunctions.cpp

@@ -30,6 +30,11 @@ static void CreatePlayerCommands()
 		return client->GetName().c_str();
 	}));
 
+	fx::ScriptEngine::RegisterNativeHandler("DOES_PLAYER_EXIST", MakeClientFunction([](fx::ScriptContext& context, const fx::ClientSharedPtr& client)
+	{
+		return true;
+	}));
+
 	fx::ScriptEngine::RegisterNativeHandler("GET_PLAYER_GUID", MakeClientFunction([](fx::ScriptContext& context, const fx::ClientSharedPtr& client)
 	{
 		return client->GetGuid().c_str();

ext/native-decls/DoesPlayerExist.md

@@ -0,0 +1,39 @@
+---
+ns: CFX
+apiset: server
+---
+## DOES_PLAYER_EXIST
+
+```c
+BOOL DOES_PLAYER_EXIST(char* playerSrc);
+```
+
+Returns whether or not the player exists
+
+## Return value
+True of the player exists, false otherwise
+
+## Examples
+
+```lua
+local deferralMessages = { "Isn't this just magical!", "We can defer all day!", "You'll get in eventually", "You're totally not going to sit here forever", "The Fruit Tree is a lie" }
+AddEventHandler("playerConnecting", function(name, setKickReason, deferrals)
+    local source = source
+    deferrals.defer()
+
+    Wait(0)
+
+
+    local messageIndex = 0
+
+    repeat
+        Wait(2000)
+        if messageIndex >= #deferralMessages then
+            deferrals.done()
+        else
+            messageIndex = messageIndex + 1
+        end
+        deferrals.update(deferralMessages[messageIndex])
+    until not DoesPlayerExist(source)
+end)
+```