feat(ext/http): Rework Deno.serve using hyper 1.0-rc3 (#18619)

This is a rewrite of the `Deno.serve` API to live on top of hyper
1.0-rc3. The code should be more maintainable long-term, and avoids some
of the slower mpsc patterns that made the older code less efficient than
it could have been.

Missing features:

- `upgradeHttp` and `upgradeHttpRaw` (`upgradeWebSocket` is available,
however).
- Automatic compression is unavailable on responses.

core/io.rs

@@ -3,6 +3,7 @@
 use std::ops::Deref;
 use std::ops::DerefMut;
 
+use bytes::Buf;
 use serde_v8::ZeroCopyBuf;
 
 /// BufView is a wrapper around an underlying contiguous chunk  of bytes. It can
@@ -26,11 +27,11 @@ enum BufViewInner {
 }
 
 impl BufView {
-  fn from_inner(inner: BufViewInner) -> Self {
+  const fn from_inner(inner: BufViewInner) -> Self {
     Self { inner, cursor: 0 }
   }
 
-  pub fn empty() -> Self {
+  pub const fn empty() -> Self {
     Self::from_inner(BufViewInner::Empty)
   }
 
@@ -65,6 +66,20 @@ impl BufView {
   }
 }
 
+impl Buf for BufView {
+  fn remaining(&self) -> usize {
+    self.len()
+  }
+
+  fn chunk(&self) -> &[u8] {
+    self.deref()
+  }
+
+  fn advance(&mut self, cnt: usize) {
+    self.advance_cursor(cnt)
+  }
+}
+
 impl Deref for BufView {
   type Target = [u8];
 
@@ -210,6 +225,20 @@ impl BufMutView {
   }
 }
 
+impl Buf for BufMutView {
+  fn remaining(&self) -> usize {
+    self.len()
+  }
+
+  fn chunk(&self) -> &[u8] {
+    self.deref()
+  }
+
+  fn advance(&mut self, cnt: usize) {
+    self.advance_cursor(cnt)
+  }
+}
+
 impl Deref for BufMutView {
   type Target = [u8];