Replace ExternalStream with new ByteStream type (#12774)

# Description
This PR introduces a `ByteStream` type which is a `Read`-able stream of
bytes. Internally, it has an enum over three different byte stream
sources:
```rust
pub enum ByteStreamSource {
    Read(Box<dyn Read + Send + 'static>),
    File(File),
    Child(ChildProcess),
}
```

This is in comparison to the current `RawStream` type, which is an
`Iterator<Item = Vec<u8>>` and has to allocate for each read chunk.

Currently, `PipelineData::ExternalStream` serves a weird dual role where
it is either external command output or a wrapper around `RawStream`.
`ByteStream` makes this distinction more clear (via `ByteStreamSource`)
and replaces `PipelineData::ExternalStream` in this PR:
```rust
pub enum PipelineData {
    Empty,
    Value(Value, Option<PipelineMetadata>),
    ListStream(ListStream, Option<PipelineMetadata>),
    ByteStream(ByteStream, Option<PipelineMetadata>),
}
```

The PR is relatively large, but a decent amount of it is just repetitive
changes.

This PR fixes #7017, fixes #10763, and fixes #12369.

This PR also improves performance when piping external commands. Nushell
should, in most cases, have competitive pipeline throughput compared to,
e.g., bash.
| Command | Before (MB/s) | After (MB/s) | Bash (MB/s) |
| -------------------------------------------------- | -------------:|
------------:| -----------:|
| `throughput \| rg 'x'` | 3059 | 3744 | 3739 |
| `throughput \| nu --testbin relay o> /dev/null` | 3508 | 8087 | 8136 |

# User-Facing Changes
- This is a breaking change for the plugin communication protocol,
because the `ExternalStreamInfo` was replaced with `ByteStreamInfo`.
Plugins now only have to deal with a single input stream, as opposed to
the previous three streams: stdout, stderr, and exit code.
- The output of `describe` has been changed for external/byte streams.
- Temporary breaking change: `bytes starts-with` no longer works with
byte streams. This is to keep the PR smaller, and `bytes ends-with`
already does not work on byte streams.
- If a process core dumped, then instead of having a `Value::Error` in
the `exit_code` column of the output returned from `complete`, it now is
a `Value::Int` with the negation of the signal number.

# After Submitting
- Update docs and book as necessary
- Release notes (e.g., plugin protocol changes)
- Adapt/convert commands to work with byte streams (high priority is
`str length`, `bytes starts-with`, and maybe `bytes ends-with`).
- Refactor the `tee` code, Devyn has already done some work on this.

---------

Co-authored-by: Devyn Cairns <devyn.cairns@gmail.com>

crates/nu-command/src/network/http/client.rs

@@ -5,10 +5,9 @@ use base64::{
     Engine,
 };
 use nu_engine::command_prelude::*;
-use nu_protocol::{BufferedReader, RawStream};
+use nu_protocol::ByteStream;
 use std::{
     collections::HashMap,
-    io::BufReader,
     path::PathBuf,
     str::FromStr,
     sync::{
@@ -119,21 +118,11 @@ pub fn response_to_buffer(
     };
 
     let reader = response.into_reader();
-    let buffered_input = BufReader::new(reader);
 
-    PipelineData::ExternalStream {
-        stdout: Some(RawStream::new(
-            Box::new(BufferedReader::new(buffered_input)),
-            engine_state.ctrlc.clone(),
-            span,
-            buffer_size,
-        )),
-        stderr: None,
-        exit_code: None,
-        span,
-        metadata: None,
-        trim_end_newline: false,
-    }
+    PipelineData::ByteStream(
+        ByteStream::read(reader, span, engine_state.ctrlc.clone()).with_known_size(buffer_size),
+        None,
+    )
 }
 
 pub fn request_add_authorization_header(
@@ -529,25 +518,25 @@ fn request_handle_response_content(
     if flags.full {
         let response_status = resp.status();
 
-        let request_headers_value = match headers_to_nu(&extract_request_headers(&request), span) {
-            Ok(headers) => headers.into_value(span),
-            Err(_) => Value::nothing(span),
-        };
+        let request_headers_value = headers_to_nu(&extract_request_headers(&request), span)
+            .and_then(|data| data.into_value(span))
+            .unwrap_or(Value::nothing(span));
 
-        let response_headers_value = match headers_to_nu(&extract_response_headers(&resp), span) {
-            Ok(headers) => headers.into_value(span),
-            Err(_) => Value::nothing(span),
-        };
+        let response_headers_value = headers_to_nu(&extract_response_headers(&resp), span)
+            .and_then(|data| data.into_value(span))
+            .unwrap_or(Value::nothing(span));
 
         let headers = record! {
             "request" => request_headers_value,
             "response" => response_headers_value,
         };
 
+        let body = consume_response_body(resp)?.into_value(span)?;
+
         let full_response = Value::record(
             record! {
                 "headers" => Value::record(headers, span),
-                "body" => consume_response_body(resp)?.into_value(span),
+                "body" => body,
                 "status" => Value::int(response_status as i64, span),
             },
             span,

crates/nu-command/src/network/url/parse.rs

@@ -42,7 +42,7 @@ impl Command for SubCommand {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        parse(input.into_value(call.head), call.head, engine_state)
+        parse(input.into_value(call.head)?, call.head, engine_state)
     }
 
     fn examples(&self) -> Vec<Example> {