Mock Mode Updates

[momintlh]

New Mock Mode with a custom manager GameObject to choose between local or browser mock mode.

Browser Mock Mode:

• Runs actual Playroom functions inside Unity editor, this should reduce building the game.

Todo:

• Different Assembly Definition for Editor only scripts so they don't get into the final build, currently using Conditional Compilation but this isn't the best solution. We can also use Editor Folder to handle.
• Handling RPC.
• Generalized way to get GameObject names for to invoke unity callbacks from the browser.

#40

[SaadBazaz]

Looks good to me. Releasing this as a beta. Resolve RPC overriding issues in next release.