Move feed fetching to crawl_feed job, DomainRequestLimiter

`DomainRequestLimiter` is a distributed version of `DomainLocks` based
on redis.

Cargo.toml

@@ -31,6 +31,7 @@ chrono = { version = "0.4", features = ["serde"] }
 clap = { version = "4.4", features = ["derive", "env"] }
 dotenvy = "0.15"
 feed-rs = "1.3"
+fred = "9"
 futures = "0.3"
 headers = "0.4"
 http = "1.0.0"
@@ -44,6 +45,7 @@ notify = "6"
 once_cell = "1.18"
 opml = "1.1"
 password-auth = "1.0"
+rand = { version = "0.8", features = ["small_rng"] }
 readability = "0.3"
 reqwest = { version = "0.12", features = ["json"] }
 serde = { version = "1", features = ["derive"] }