[diskann-providers] Remove the LRU dependency and make vfs and serde_json optional. (#733)

Remove the LRU crate as a dependency of `diskann-providers` since it is
unused and triggering a dependabot alert. In addition, make the
following dependencies optionsl:

* `vfs` - activated by the "virtual_storage" feature.
* `serde_json` - activated by the "bf_tree" feature.

Finally, `cbindgen` and `csv` are removed from the workspace level
`Cargo.toml` since they are unused.

Author: hildebrandmw

Cargo.lock

@@ -72,11 +72,9 @@ bincode = "1.3.3"
 bit-set = "0.8.0"
 bytemuck = "1.23.0"
 byteorder = "1.5.0"
-cbindgen = "0.28.0"
 cfg-if = "1.0.0"
 clap = "4.5.45"
 criterion = "0.5.1"
-csv = "1.3.1"
 dashmap = "6.1.0"
 futures-util = { version = "0.3.31", default-features = false }
 half = "2.6.0"

Cargo.toml

@@ -18,7 +18,6 @@ half = { workspace = true, features = ["bytemuck", "num-traits"] }
 hashbrown.workspace = true
 num-traits.workspace = true
 once_cell.workspace = true
-lru = "0.12.3"
 rand.workspace = true
 rayon.workspace = true
 serde = { workspace = true, features = ["derive"] }
@@ -32,7 +31,6 @@ diskann-wide = { workspace = true }
 arc-swap.workspace = true
 tracing.workspace = true
 diskann-linalg = { workspace = true }
-vfs = { workspace = true }
 diskann = { workspace = true }
 diskann-utils = { workspace = true }
 diskann-quantization = { workspace = true, features = ["rayon"] }
@@ -43,7 +41,8 @@ anyhow.workspace = true
 prost = "0.14.1"
 futures-util.workspace = true
 polonius-the-crab = { version = "0.5.0", optional = true }
-serde_json.workspace = true
+serde_json = { workspace = true, optional = true }
+vfs = { workspace = true, optional = true }
 
 [dev-dependencies]
 approx.workspace = true
@@ -52,9 +51,9 @@ iai-callgrind.workspace = true
 itertools.workspace = true
 tempfile.workspace = true
 rstest.workspace = true
-serde_json.workspace = true
 tokio = { workspace = true, features = ["full"] }
 proptest.workspace = true
+vfs.workspace = true
 
 [[bench]]
 name = "bench_main"
@@ -79,9 +78,9 @@ targets = [
 default = []
 perf_test = ["dep:opentelemetry"]
 testing = ["dep:tempfile"]
-bf_tree = ["dep:bf-tree", "dep:polonius-the-crab"]
+bf_tree = ["dep:bf-tree", "dep:polonius-the-crab", "dep:serde_json"]
 experimental_diversity_search = ["diskann/experimental_diversity_search"]
-virtual_storage = []
+virtual_storage = ["dep:vfs"]
 
 # Some 'cfg's in the source tree will be flagged by `cargo clippy -j 2 --workspace --no-deps --all-targets -- -D warnings`
 [lints.rust]