General cleanup of module loading code, tried to reduce indentation in various methods
on "JsRuntime" to improve readability.
Added "JsRuntime::handle_scope" helper function, which returns a "v8::HandleScope".
This was done to reduce a code pattern that happens all over the "deno_core".
Additionally if event loop hangs during loading of dynamic modules a list of
currently pending dynamic imports is printed.
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)
- Improves op performance.
- Handle op-metadata (errors, promise IDs) explicitly in the op-layer vs
per op-encoding (aka: out-of-payload).
- Remove shared queue & custom "asyncHandlers", all async values are
returned in batches via js_recv_cb.
- The op-layer should be thought of as simple function calls with little
indirection or translation besides the conceptually straightforward
serde_v8 bijections.
- Preserve concepts of json/bin/min as semantic groups of their
inputs/outputs instead of their op-encoding strategy, preserving these
groups will also facilitate partial transitions over to v8 Fast API for the
"min" and "bin" groups
