Dota 2 update for March 12, 2019

Custom Games API:

• Added GetDedicatedServerKeyV2 which utilizes a new approach for securing/generating the keys. Any custom game that relies on GetDedicatedServerKey to communicate with its backend will want to switch to the V2 version as soon as possible.
• To give custom game authors time to switch to the new system, GetDedicatedServerKey will remain unchanged until 3/31/2019, after which will be automatically switched to V2.
• When playing on local/unofficial servers, GetDedicatedServerV2 will return special values to make the state more clear for developers (e.g. Invalid_NotOnDedicatedServer).