feat: account verification + mail config in admin area

client/graph/admin/mail/mail-mutation-save-config.gql

@@ -0,0 +1,36 @@
+mutation (
+  $senderName: String!,
+  $senderEmail: String!,
+  $host: String!,
+  $port: Int!,
+  $secure: Boolean!,
+  $user: String!,
+  $pass: String!,
+  $useDKIM: Boolean!,
+  $dkimDomainName: String!,
+  $dkimKeySelector: String!,
+  $dkimPrivateKey: String!
+) {
+  mail {
+    updateConfig(
+      senderName: $senderName,
+      senderEmail: $senderEmail,
+      host: $host,
+      port: $port,
+      secure: $secure,
+      user: $user,
+      pass: $pass,
+      useDKIM: $useDKIM,
+      dkimDomainName: $dkimDomainName,
+      dkimKeySelector: $dkimKeySelector,
+      dkimPrivateKey: $dkimPrivateKey
+    ) {
+      responseResult {
+        succeeded
+        errorCode
+        slug
+        message
+      }
+    }
+  }
+}