Fixed more missing namespaces

Summary: See the previous diffs, we pollute the global namespace here and there. Found some more missing namespace wrappers. Tried to wrap `FlipperStep` as well, which passed tests but gave weird linking errors in Wilde, so reverted that part (the name is not very ambiguous anyway)

Reviewed By: cekkaewnumchai

Differential Revision: D24193109

fbshipit-source-id: 111c479e421fdb321e898f948586229f30a7d777

xplat/Flipper/CertificateUtils.cpp

@@ -14,6 +14,9 @@
 #include <openssl/rsa.h>
 #include <cstring>
 
+namespace facebook {
+namespace flipper {
+
 void free(
     EVP_PKEY* pKey,
     X509_REQ* x509_req,
@@ -222,3 +225,6 @@ void free(
   BIO_free_all(privateKey);
   BIO_free_all(csrBio);
 }
+
+} // namespace flipper
+} // namespace facebook