Added a variant of the test that uses HashiCorp Vault to manage te

Certificate Authorities.

vault_make_client_cert.sh

@@ -0,0 +1,13 @@
+# Generate the client key and CSR locally, the key is never sent to Vault
+openssl req \
+    -newkey rsa:4096 \
+    -keyout client_key.pem \
+    -noenc \
+    -subj "/CN=test-client" \
+    -out client.csr
+
+# Sign the client CSR
+vault write -field=certificate pki_int/sign/wif-client \
+    csr=@client.csr \
+    common_name=test-client \
+    ttl=8760h > client_cert.pem