Allow checking arbitrary domain records

[paw-hub]

Add customer ID as an optional field for support to assist with custom domain troubleshooting.

tutadb#1299

Test notes

• Go to a customer in the admin client and click "Check DNS records for another domain...". Enter "gmail.com" and take note of t-verify value displayed.
  • Log into this customer in the Tutanota client, attempt to add "gmail.com" as a custom domain, and verify that it wants the same t-verify value to be added.
• Go to a different customer. Enter "gmail.com" in the admin client and verify it shows the same information except for a different hash after t-verify.
  • For the same customer, enter "hotmail.com" in the admin client and verify it still shows a different t-verify value.

[ganthern]

• I'll need some test notes
• what's up with all the models suddenly being compatible since version 0? has something changed here?

[mpfau]

What puzzles me is that we remove schemas for already outdated sys/storage and tutanota models.

@ganthern do you have an idea on how that could happen?

[paw-hub]

The issue was due to a change in SchemeGenerator.js#isPersistentType that was there for some reason. Vitor and I discussed it and were not sure why it was there besides maybe trying to work around a compile error after rebase for some reason, so we rolled it back.

It should be fixed in the model now. Thanks for catching that!