refactor: move gateway and vault components to new locations

gateway/context/credentials.go

@@ -0,0 +1,19 @@
+package context
+
+import (
+	"github.com/go-webauthn/webauthn/protocol"
+)
+
+func (c *GatewayContext) NewChallenge() string {
+	chal, _ := protocol.CreateChallenge()
+	chalStr := chal.String()
+	return chalStr
+}
+
+func (cc *GatewayContext) ListCredentials(handle string) ([]*CredentialDescriptor, error) {
+	creds, err := cc.GetCredentialsByHandle(bgCtx(), handle)
+	if err != nil {
+		return nil, err
+	}
+	return CredentialArrayToDescriptors(creds), nil
+}