Make guest side forwarder agent buildable

Bug: 340126051
Test: cd build/debian/forwarder_guest && cargo build
Change-Id: I13eec2c3daf59412de679258142de66f0f60002d
diff --git a/libs/libforwarder/Cargo.toml b/libs/libforwarder/Cargo.toml
new file mode 100644
index 0000000..9f3f341
--- /dev/null
+++ b/libs/libforwarder/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "forwarder"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+libc = "0.2.159"
+remain = "0.2.14"
+vsock = "0.5.1"