feat: Adjust directory name for nargo codegen-verifier (#1009)

Author: longfin

crates/nargo_cli/src/constants.rs

@@ -1,6 +1,6 @@
 // Directories
-/// The directory for the `nargo contract` command output
-pub(crate) const CONTRACT_DIR: &str = "contract";
+/// The directory for the `nargo codegen-verifier` command output
+pub(crate) const CONTRACT_DIR: &str = "contracts";
 /// The directory to store serialized circuit proofs.
 pub(crate) const PROOFS_DIR: &str = "proofs";
 /// The directory to store Noir source files