Respawn Instance when OOM

[nicholasjackson]

It is possible for a plugin instance to exceed the allocated WebAssembly modules memory. Normally memory will grow as required but every instance should have a hard limit.

In the instance that a plugin exceeds memory it should be shut down and either automatically restarted or the error message passed to the creator should be descriptive enough to allow them to restart. The later option might be the best approach for the principle of least surprise.