Move stream items into tokio-stream (#3277)

This change removes all references to `Stream` from
within the `tokio` crate and moves them into a new
`tokio-stream` crate. Most types have had their
`impl Stream` removed as well in-favor of their
inherent methods.

Closes #2870

tokio-util/src/io/read_buf.rs

@@ -13,7 +13,7 @@ use tokio::io::AsyncRead;
 ///
 /// ```
 /// use bytes::{Bytes, BytesMut};
-/// use tokio::stream;
+/// use tokio_stream as stream;
 /// use tokio::io::Result;
 /// use tokio_util::io::{StreamReader, read_buf};
 /// # #[tokio::main]

tokio-util/src/io/reader_stream.rs

@@ -18,7 +18,7 @@ pin_project! {
     /// ```
     /// # #[tokio::main]
     /// # async fn main() -> std::io::Result<()> {
-    /// use tokio::stream::StreamExt;
+    /// use tokio_stream::StreamExt;
     /// use tokio_util::io::ReaderStream;
     ///
     /// // Create a stream of data.
@@ -40,7 +40,7 @@ pin_project! {
     ///
     /// [`AsyncRead`]: tokio::io::AsyncRead
     /// [`StreamReader`]: crate::io::StreamReader
-    /// [`Stream`]: tokio::stream::Stream
+    /// [`Stream`]: tokio_stream::Stream
     #[derive(Debug)]
     pub struct ReaderStream<R> {
         // Reader itself.
@@ -58,7 +58,7 @@ impl<R: AsyncRead> ReaderStream<R> {
     /// `Result<Bytes, std::io::Error>`.
     ///
     /// [`AsyncRead`]: tokio::io::AsyncRead
-    /// [`Stream`]: tokio::stream::Stream
+    /// [`Stream`]: tokio_stream::Stream
     pub fn new(reader: R) -> Self {
         ReaderStream {
             reader: Some(reader),

tokio-util/src/io/stream_reader.rs

@@ -21,7 +21,7 @@ pin_project! {
     /// # async fn main() -> std::io::Result<()> {
     ///
     /// // Create a stream from an iterator.
-    /// let stream = tokio::stream::iter(vec![
+    /// let stream = tokio_stream::iter(vec![
     ///     Result::Ok(Bytes::from_static(&[0, 1, 2, 3])),
     ///     Result::Ok(Bytes::from_static(&[4, 5, 6, 7])),
     ///     Result::Ok(Bytes::from_static(&[8, 9, 10, 11])),
@@ -51,7 +51,7 @@ pin_project! {
     /// ```
     ///
     /// [`AsyncRead`]: tokio::io::AsyncRead
-    /// [`Stream`]: tokio::stream::Stream
+    /// [`Stream`]: tokio_stream::Stream
     /// [`ReaderStream`]: crate::io::ReaderStream
     #[derive(Debug)]
     pub struct StreamReader<S, B> {