feat: use postcard for redis serde (#6956)

* redo error handling in xredis

* give proper types to metadata fields

* add round-trip tests

* inline loader enum metadata fields

* postcard roundtrips

* prepare

* bump redis key version

* serde-binhum

* clippy

* fix

* fix frontend checking existence of component fields rather than non-null-ness

* prepare

packages/xredis/Cargo.toml

@@ -10,8 +10,10 @@ ariadne = { workspace = true }
 chrono = { workspace = true }
 dashmap = { workspace = true }
 deadpool-redis = { workspace = true, features = ["cluster-async"] }
+eyre = { workspace = true }
 futures = { workspace = true }
 lz4_flex = { workspace = true }
+postcard = { workspace = true }
 prometheus = { workspace = true }
 redis = { workspace = true, features = [
   "ahash",
@@ -20,7 +22,6 @@ redis = { workspace = true, features = [
   "tokio-comp"
 ] }
 serde = { workspace = true, features = ["derive"] }
-serde_json = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true, features = ["rt", "sync", "time"] }
 tracing = { workspace = true }