task_local context over context objects

- interner impls logically separate from API in orchid-base (default host interner still in base for testing)
- error reporting, logging, and a variety of other features passed down via context in extension, not yet in host to maintain library-ish profile, should consider options
- no global spawn mechanic, the host has a spawn function but extensions only get a stash for enqueuing async work in sync callbacks which is then explicitly, manually, and with strict order popped and awaited
- still deadlocks nondeterministically for some ungodly reason

orchid-extension/src/ext_port.rs

@@ -0,0 +1,12 @@
+use std::pin::Pin;
+use std::rc::Rc;
+
+use futures::future::LocalBoxFuture;
+use futures::{AsyncRead, AsyncWrite};
+
+pub struct ExtPort {
+	pub input: Pin<Box<dyn AsyncRead>>,
+	pub output: Pin<Box<dyn AsyncWrite>>,
+	pub log: Pin<Box<dyn AsyncWrite>>,
+	pub spawn: Rc<dyn Fn(LocalBoxFuture<'static, ()>)>,
+}