chore(proxy): vendor a subset of rust-postgres (#9930)

Our rust-postgres fork is getting messy. Mostly because proxy wants more
control over the raw protocol than tokio-postgres provides. As such,
it's diverging more and more. Storage and compute also make use of
rust-postgres, but in more normal usage, thus they don't need our crazy
changes.

Idea: 
* proxy maintains their subset
* other teams use a minimal patch set against upstream rust-postgres

Reviewing this code will be difficult. To implement it, I
1. Copied tokio-postgres, postgres-protocol and postgres-types from
https://github.com/neondatabase/rust-postgres/tree/00940fcdb57a8e99e805297b75839e7c4c7b1796
2. Updated their package names with the `2` suffix to make them compile
in the workspace.
3. Updated proxy to use those packages
4. Copied in the code from tokio-postgres-rustls 0.13 (with some patches
applied https://github.com/jbg/tokio-postgres-rustls/pull/32
https://github.com/jbg/tokio-postgres-rustls/pull/33)
5. Removed as much dead code as I could find in the vendored libraries
6. Updated the tokio-postgres-rustls code to use our existing channel
binding implementation

proxy/src/serverless/backend.rs

@@ -333,7 +333,7 @@ impl PoolingBackend {
             debug!("setting up backend session state");
 
             // initiates the auth session
-            if let Err(e) = client.query("select auth.init()", &[]).await {
+            if let Err(e) = client.execute("select auth.init()", &[]).await {
                 discard.discard();
                 return Err(e.into());
             }

proxy/src/serverless/conn_pool.rs

@@ -6,9 +6,10 @@ use std::task::{ready, Poll};
 use futures::future::poll_fn;
 use futures::Future;
 use smallvec::SmallVec;
+use tokio::net::TcpStream;
 use tokio::time::Instant;
 use tokio_postgres::tls::NoTlsStream;
-use tokio_postgres::{AsyncMessage, Socket};
+use tokio_postgres::AsyncMessage;
 use tokio_util::sync::CancellationToken;
 use tracing::{error, info, info_span, warn, Instrument};
 #[cfg(test)]
@@ -57,7 +58,7 @@ pub(crate) fn poll_client<C: ClientInnerExt>(
     ctx: &RequestContext,
     conn_info: ConnInfo,
     client: C,
-    mut connection: tokio_postgres::Connection<Socket, NoTlsStream>,
+    mut connection: tokio_postgres::Connection<TcpStream, NoTlsStream>,
     conn_id: uuid::Uuid,
     aux: MetricsAuxInfo,
 ) -> Client<C> {

proxy/src/serverless/local_conn_pool.rs

@@ -24,10 +24,11 @@ use p256::ecdsa::{Signature, SigningKey};
 use parking_lot::RwLock;
 use serde_json::value::RawValue;
 use signature::Signer;
+use tokio::net::TcpStream;
 use tokio::time::Instant;
 use tokio_postgres::tls::NoTlsStream;
 use tokio_postgres::types::ToSql;
-use tokio_postgres::{AsyncMessage, Socket};
+use tokio_postgres::AsyncMessage;
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, error, info, info_span, warn, Instrument};
 
@@ -163,7 +164,7 @@ pub(crate) fn poll_client<C: ClientInnerExt>(
     ctx: &RequestContext,
     conn_info: ConnInfo,
     client: C,
-    mut connection: tokio_postgres::Connection<Socket, NoTlsStream>,
+    mut connection: tokio_postgres::Connection<TcpStream, NoTlsStream>,
     key: SigningKey,
     conn_id: uuid::Uuid,
     aux: MetricsAuxInfo,
@@ -286,11 +287,11 @@ impl ClientInnerCommon<tokio_postgres::Client> {
             let token = resign_jwt(&local_data.key, payload, local_data.jti)?;
 
             // initiates the auth session
-            self.inner.simple_query("discard all").await?;
+            self.inner.batch_execute("discard all").await?;
             self.inner
-                .query(
+                .execute(
                     "select auth.jwt_session_init($1)",
-                    &[&token as &(dyn ToSql + Sync)],
+                    &[&&*token as &(dyn ToSql + Sync)],
                 )
                 .await?;