Wrap SandboxBuilder, Sandbox and ResultSet before passing to plugins

[jonasfj]

Before we pass SandboxBuilder, Sandbox and ResultSet to plugins we should wrap with a simple wrapper that captures panic in any calls...

We might also want to use this forbid (or make impossible via. type-system) certain methods like Sandbox.WaitForResult() which plugins have no business calling.. Or ResultSet.Dispose(), clearly plugins should be calling those, so maybe we should remove the methods from the interfaces...

[jonasfj]

These wrapper should also apply a reasonable timeout... If NewShell takes more than 15min we can assume the process has deadlocked..