safekeeper: use protobuf for sending compressed records to pageserver (#9821)

## Problem

https://github.com/neondatabase/neon/pull/9746 lifted decoding and
interpretation of WAL to the safekeeper.
This reduced the ingested amount on the pageservers by around 10x for a
tenant with 8 shards, but doubled
the ingested amount for single sharded tenants.

Also, https://github.com/neondatabase/neon/pull/9746 uses bincode which
doesn't support schema evolution.
Technically the schema can be evolved, but it's very cumbersome.

## Summary of changes

This patch set addresses both problems by adding protobuf support for
the interpreted wal records and adding compression support. Compressed
protobuf reduced the ingested amount by 100x on the 32 shards
`test_sharded_ingest` case (compared to non-interpreted proto). For the
1 shard case the reduction is 5x.

Sister change to `rust-postgres` is
[here](https://github.com/neondatabase/rust-postgres/pull/33).

## Links

Related: https://github.com/neondatabase/neon/issues/9336
Epic: https://github.com/neondatabase/neon/issues/9329

libs/utils/src/postgres_client.rs

@@ -7,40 +7,31 @@ use postgres_connection::{parse_host_port, PgConnectionConfig};
 
 use crate::id::TenantTimelineId;
 
-/// Postgres client protocol types
-#[derive(
-    Copy,
-    Clone,
-    PartialEq,
-    Eq,
-    strum_macros::EnumString,
-    strum_macros::Display,
-    serde_with::DeserializeFromStr,
-    serde_with::SerializeDisplay,
-    Debug,
-)]
-#[strum(serialize_all = "kebab-case")]
-#[repr(u8)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug, serde::Serialize, serde::Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum InterpretedFormat {
+    Bincode,
+    Protobuf,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum Compression {
+    Zstd { level: i8 },
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+#[serde(tag = "type", content = "args")]
+#[serde(rename_all = "kebab-case")]
 pub enum PostgresClientProtocol {
     /// Usual Postgres replication protocol
     Vanilla,
     /// Custom shard-aware protocol that replicates interpreted records.
     /// Used to send wal from safekeeper to pageserver.
-    Interpreted,
-}
-
-impl TryFrom<u8> for PostgresClientProtocol {
-    type Error = u8;
-
-    fn try_from(value: u8) -> Result<Self, Self::Error> {
-        Ok(match value {
-            v if v == (PostgresClientProtocol::Vanilla as u8) => PostgresClientProtocol::Vanilla,
-            v if v == (PostgresClientProtocol::Interpreted as u8) => {
-                PostgresClientProtocol::Interpreted
-            }
-            x => return Err(x),
-        })
-    }
+    Interpreted {
+        format: InterpretedFormat,
+        compression: Option<Compression>,
+    },
 }
 
 pub struct ConnectionConfigArgs<'a> {
@@ -63,7 +54,10 @@ impl<'a> ConnectionConfigArgs<'a> {
             "-c".to_owned(),
             format!("timeline_id={}", self.ttid.timeline_id),
             format!("tenant_id={}", self.ttid.tenant_id),
-            format!("protocol={}", self.protocol as u8),
+            format!(
+                "protocol={}",
+                serde_json::to_string(&self.protocol).unwrap()
+            ),
         ];
 
         if self.shard_number.is_some() {