Add a K2V client library and CLI (#303)

lib.rs could use getting split in modules, but I'm not sure how exactly

Co-authored-by: trinity-1686a <trinity@deuxfleurs.fr>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/303
Co-authored-by: trinity-1686a <trinity.pointard@gmail.com>
Co-committed-by: trinity-1686a <trinity.pointard@gmail.com>

src/k2v-client/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "k2v-client"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+base64 = "0.13.0"
+http = "0.2.6"
+rusoto_core = "0.48.0"
+rusoto_credential = "0.48.0"
+rusoto_signature = "0.48.0"
+serde = "1.0.137"
+serde_json = "1.0.81"
+thiserror = "1.0.31"
+tokio = "1.17.0"
+
+# cli deps
+clap = { version = "3.1.18", optional = true, features = ["derive", "env"] }
+garage_util = { path = "../util", optional = true }
+
+
+[features]
+cli = ["clap", "tokio/fs", "tokio/io-std", "garage_util"]
+
+[[bin]]
+name = "k2v-cli"
+required-features = ["cli"]