[Remote signer] Fold signer into Lighthouse repository (#1852)

The remote signer relies on the `types` and `crypto/bls` crates from Lighthouse. Moreover, a number of tests of the remote signer consumption of LH leverages this very signer, making any important update a potential dependency nightmare.

Co-authored-by: Paul Hauner <paul@paulhauner.com>

remote_signer/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "remote_signer"
+version = "0.2.0"
+authors = ["Sigma Prime <contact@sigmaprime.io>"]
+edition = "2018"
+
+[features]
+# Compiles the BLS crypto code so that the binary is portable across machines.
+portable = ["bls/supranational-portable"]
+# Uses the slower Milagro BLS library, which is written in native Rust.
+milagro = ["bls/milagro"]
+
+[dev-dependencies]
+client_backend = { path = "./backend", package = "remote_signer_backend" }
+helpers = { path = "../testing/remote_signer_test", package = "remote_signer_test" }
+
+[dependencies]
+bls = { path = "../crypto/bls" }
+clap = "2.33.3"
+client = { path = "./client", package = "remote_signer_client" }
+environment = { path = "../lighthouse/environment" }
+serde_json = "1.0.58"
+slog = { version = "2.5.2", features = ["max_level_trace"] }
+types = { path = "../consensus/types"}