breaking: fix: kcp2k V1.16

- fix: SendUnreliable respects ArraySegment.Offset
- fix: potential bug with negative length (see PR MirrorNetworking#2)
- breaking: removed pause handling because it's not necessary for Mirror anymore

breaking: removed legacy NetworkVisibility system

syntax

fix: InterestManagement Awake

- Don't check for active server or client
- static `aoi` must always be set

fix: NetworkManagerHUD use NetworkManager.singleton

fix: RuntimeInitializeOnLoadMethod BeforeSceneLoad

- RuntimeInitializeLoadType.BeforeSceneLoad is requred so methods with this attribute fire BEFORE Awake

fix: Fixed PlayerCamera scripts in examples

- can't unparent camera in OnDisable
- Player may be in a subscene so put camera in active scene after unparenting so it's not lost if additive is unloaded.
- Moving player object between subscenes unexpectedly fires OnDisable & OnEnable...who knew?

syntax

fix: NetworkStartPosition use Start instead of Awake

- NetworkManager::ResetStatics fires after scene object's MonoB.Awake and wipes the static list

fix: moved MirrorIcon to Editor folder

- excludes it from builds