Even if bootstrapping the JS runtime is low level, it's an abstraction leak of
core to require users to call `Deno.core.ops()` in JS space.
So instead we're introducing a `JsRuntime::sync_ops_cache()` method,
once we have runtime extensions a new runtime will ensure the ops
cache is setup (for the provided extensions) and then loading/unloading
plugins should be the only operations that require op cache syncs
- register builtin v8 errors in core.js so consumers don't have to
- remove complexity of error args handling (consumers must provide a
constructor with custom args, core simply provides msg arg)
