feat(tvix/nar-bridge): support uploading NAR files

This ingests NAR files into the {Blob,Directory}Service, which are
already part of the AppState.

As we then need to correlate the root node to the uploaded PathInfo, we
need to keep a (short-lived) lookup table from NARHash to root node
around. We insert it into a `LruCache` after the NAR is uploaded, and
use `peek()` to do the lookup, which doesn't update the LRU list.

Change-Id: I48a4c6246bacf76559c5a4ccad2a0bc25c1b7900
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11986
Tested-by: BuildkiteCI
Reviewed-by: Brian Olsen <me@griff.name>

tvix/nar-bridge/Cargo.toml

@@ -8,6 +8,7 @@ axum = { version = "0.7.5", features = ["http2"] }
 bytes = "1.4.0"
 clap = { version = "4.0", features = ["derive", "env"] }
 data-encoding = "2.3.3"
+futures = "0.3.30"
 itertools = "0.12.0"
 prost = "0.12.1"
 nix-compat = { path = "../nix-compat", features = ["async"] }
@@ -23,6 +24,8 @@ tracing = "0.1.37"
 tracing-subscriber = "0.3.16"
 url = "2.4.0"
 serde = { version = "1.0.204", features = ["derive"] }
+lru = "0.12.3"
+parking_lot = "0.12.3"
 
 [build-dependencies]
 prost-build = "0.12.1"