Add safekeeper membership conf to control file. (#10196)

## Problem

https://github.com/neondatabase/neon/issues/9965

## Summary of changes

Add safekeeper membership configuration struct itself and storing it in
the control file. In passing also add creation timestamp to the control
file (there were cases where I wanted it in the past).

Remove obsolete unused PersistedPeerInfo struct from control file (still
keep it control_file_upgrade.rs to have it in old upgrade code).

Remove the binary representation of cfile in the roundtrip test.
Updating it is annoying, and we still test the actual roundtrip.

Also add configuration to timeline creation http request, currently used
only in one python test. In passing, slightly change LSNs meaning in the
request: normally start_lsn is passed (the same as ancestor_start_lsn in
similar pageserver call), but we allow specifying higher commit_lsn for
manual intervention if needed. Also when given LSN initialize
term_history with it.

safekeeper/tests/walproposer_sim/safekeeper.rs

@@ -21,7 +21,7 @@ use safekeeper::{
     wal_storage::Storage,
     SafeKeeperConf,
 };
-use safekeeper_api::ServerInfo;
+use safekeeper_api::{membership::Configuration, ServerInfo};
 use tracing::{debug, info_span, warn};
 use utils::{
     id::{NodeId, TenantId, TenantTimelineId, TimelineId},
@@ -96,8 +96,13 @@ impl GlobalMap {
         let commit_lsn = Lsn::INVALID;
         let local_start_lsn = Lsn::INVALID;
 
-        let state =
-            TimelinePersistentState::new(&ttid, server_info, vec![], commit_lsn, local_start_lsn)?;
+        let state = TimelinePersistentState::new(
+            &ttid,
+            Configuration::empty(),
+            server_info,
+            commit_lsn,
+            local_start_lsn,
+        )?;
 
         let disk_timeline = self.disk.put_state(&ttid, state);
         let control_store = DiskStateStorage::new(disk_timeline.clone());