Add client write support to NetworkVariable

[Haruwolf]

NetworkVariables don't have more permissions in 1.0.0 only server can write them.

If I can give a suggestion, adding a way to client change a local variable and server taking to Network Variable, would be good.

[Cratesmith]

Seconding issue about not being able to have client written network vairables.
This is a major workflow problem for clientside driven elements if the only option is to RPC all state changes to the server.

[JesseOlmer]

Fixed by #1762