feat(ops): relational ops (#18023)

Join two independent ops into one. A fast impl of one + a slow callback
of another. Here's an example showing optimized paths for latin-1 via
fast call and the next-best fallback using V8 apis.

```rust
#[op(v8)]
fn op_encoding_encode_into_fallback(
  scope: &mut v8::HandleScope,
  input: serde_v8::Value,
// ...

#[op(fast, slow = op_encoding_encode_into_fallback)]
fn op_encoding_encode_into(
  input: Cow<'_, str>,
// ...
```

Benchmark results of the fallback path:
```
time target/release/deno run -A --unstable ./cli/tests/testdata/benches/text_encoder_into_perf.js
________________________________________________________
Executed in   70.90 millis    fish           external
   usr time   57.76 millis    0.23 millis   57.53 millis
   sys time   17.02 millis    1.28 millis   15.74 millis

target/release/deno_main run -A --unstable ./cli/tests/testdata/benches/text_encoder_into_perf.js
________________________________________________________
Executed in  154.00 millis    fish           external
   usr time   67.14 millis    0.26 millis   66.88 millis
   sys time   38.82 millis    1.47 millis   37.35 millis
```

1 files changed, 22 insertions, 1 deletions

diff --git a/ext/web/lib.rs b/ext/web/lib.rs
index 2f59636fe..76095810e 100644
--- a/ext/web/lib.rs
+++ b/ext/web/lib.rs
@@ -350,7 +350,28 @@ impl Resource for TextDecoderResource {
   }
 }
 
-#[op]
+#[op(v8)]
+fn op_encoding_encode_into_fallback(
+  scope: &mut v8::HandleScope,
+  input: serde_v8::Value,
+  buffer: &mut [u8],
+  out_buf: &mut [u32],
+) -> Result<(), AnyError> {
+  let s = v8::Local::<v8::String>::try_from(input.v8_value)?;
+
+  let mut nchars = 0;
+  out_buf[1] = s.write_utf8(
+    scope,
+    buffer,
+    Some(&mut nchars),
+    v8::WriteOptions::NO_NULL_TERMINATION
+      | v8::WriteOptions::REPLACE_INVALID_UTF8,
+  ) as u32;
+  out_buf[0] = nchars as u32;
+  Ok(())
+}
+
+#[op(fast, slow = op_encoding_encode_into_fallback)]
 fn op_encoding_encode_into(
   input: Cow<'_, str>,
   buffer: &mut [u8],