Add a Rust workspace

Define a workspace in rust/ so that bssl-sys and bssl-crypto crates can
be built and tested at once from the rust/ directory:
  cd rust
  cargo build --workspace
  cargo test --workspace

(The --workspace arg is optional since this is a virtual manifest; the
default is the whole workspace.)

Change-Id: I88fb738a96837ce19b53fdaeabe91491fa0240fd
Bug: 42290446
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/80527
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Auto-Submit: Lily Chen <chlily@google.com>

rust/Cargo.lock

diff --git a/rust/Cargo.lock b/rust/Cargo.lock
new file mode 100644
index 0000000..d1c658f
--- /dev/null
+++ b/rust/Cargo.lock
@@ -0,0 +1,14 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "bssl-crypto"
+version = "0.2.0"
+dependencies = [
+ "bssl-sys",
+]
+
+[[package]]
+name = "bssl-sys"
+version = "0.1.0"

rust/Cargo.toml

diff --git a/rust/Cargo.toml b/rust/Cargo.toml
new file mode 100644
index 0000000..a0689b3
--- /dev/null
+++ b/rust/Cargo.toml
@@ -0,0 +1,6 @@
+[workspace]
+members = [
+  "bssl-crypto",
+  "bssl-sys",
+]
+resolver = "3"