Restructure remote client crate, consolidate SSH logic (#36967)

This is a pure refactor that consolidates all SSH remoting logic such
that it should be straightforward to add another transport to the
remoting system.

Release Notes:

- N/A

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>

crates/remote/src/protocol.rs

@@ -51,6 +51,16 @@ pub async fn write_message<S: AsyncWrite + Unpin>(
     Ok(())
 }
 
+pub async fn write_size_prefixed_buffer<S: AsyncWrite + Unpin>(
+    stream: &mut S,
+    buffer: &mut Vec<u8>,
+) -> Result<()> {
+    let len = buffer.len() as u32;
+    stream.write_all(len.to_le_bytes().as_slice()).await?;
+    stream.write_all(buffer).await?;
+    Ok(())
+}
+
 pub async fn read_message_raw<S: AsyncRead + Unpin>(
     stream: &mut S,
     buffer: &mut Vec<u8>,