feat: improve the serde impl for several types(Lsn, TenantId, TimelineId ...) (#5335)

Improve the serde impl for several types (`Lsn`, `TenantId`,
`TimelineId`) by making them sensitive to
`Serializer::is_human_readadable` (true for json, false for bincode).

Fixes #3511 by:
- Implement the custom serde for `Lsn`
- Implement the custom serde for `Id`
- Add the helper module `serde_as_u64` in `libs/utils/src/lsn.rs`
- Remove the unnecessary attr `#[serde_as(as = "DisplayFromStr")]` in
all possible structs

Additionally some safekeeper types gained serde tests.

---------

Co-authored-by: Joonas Koivunen <joonas@neon.tech>

libs/safekeeper_api/src/models.rs

@@ -1,23 +1,18 @@
 use serde::{Deserialize, Serialize};
-use serde_with::{serde_as, DisplayFromStr};
 
 use utils::{
     id::{NodeId, TenantId, TimelineId},
     lsn::Lsn,
 };
 
-#[serde_as]
 #[derive(Serialize, Deserialize)]
 pub struct TimelineCreateRequest {
-    #[serde_as(as = "DisplayFromStr")]
     pub tenant_id: TenantId,
-    #[serde_as(as = "DisplayFromStr")]
     pub timeline_id: TimelineId,
     pub peer_ids: Option<Vec<NodeId>>,
     pub pg_version: u32,
     pub system_id: Option<u64>,
     pub wal_seg_size: Option<u32>,
-    #[serde_as(as = "DisplayFromStr")]
     pub commit_lsn: Lsn,
     // If not passed, it is assigned to the beginning of commit_lsn segment.
     pub local_start_lsn: Option<Lsn>,
@@ -28,7 +23,6 @@ fn lsn_invalid() -> Lsn {
 }
 
 /// Data about safekeeper's timeline, mirrors broker.proto.
-#[serde_as]
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct SkTimelineInfo {
     /// Term.
@@ -36,25 +30,19 @@ pub struct SkTimelineInfo {
     /// Term of the last entry.
     pub last_log_term: Option<u64>,
     /// LSN of the last record.
-    #[serde_as(as = "DisplayFromStr")]
     #[serde(default = "lsn_invalid")]
     pub flush_lsn: Lsn,
     /// Up to which LSN safekeeper regards its WAL as committed.
-    #[serde_as(as = "DisplayFromStr")]
     #[serde(default = "lsn_invalid")]
     pub commit_lsn: Lsn,
     /// LSN up to which safekeeper has backed WAL.
-    #[serde_as(as = "DisplayFromStr")]
     #[serde(default = "lsn_invalid")]
     pub backup_lsn: Lsn,
     /// LSN of last checkpoint uploaded by pageserver.
-    #[serde_as(as = "DisplayFromStr")]
     #[serde(default = "lsn_invalid")]
     pub remote_consistent_lsn: Lsn,
-    #[serde_as(as = "DisplayFromStr")]
     #[serde(default = "lsn_invalid")]
     pub peer_horizon_lsn: Lsn,
-    #[serde_as(as = "DisplayFromStr")]
     #[serde(default = "lsn_invalid")]
     pub local_start_lsn: Lsn,
     /// A connection string to use for WAL receiving.