Add retry handler for expired CSRF tokens

[ChristophWurst]

For nextcloud/mail#5714

• Requires Add optional maintenance mode retry handler for short downtimes #510

This fetches a new CSRF token right when it doesn't validate anymore.

How to test

1. Log into Nextcloud
2. Open a second tab
3. Log out on the second tab
4. Log in again on the second tab
5. Trigger an action with a HTTP request on the first tab

On master: request fails with 412, the error bubbles up and the action fails.
Here: request fails with 412, there is another request to fetch a CSRF token, the request is sent again and works. The action succeeds.

[ChristophWurst]

Works ✨

[vinicius73]

Question: After request the new CSRF, the other tab (in the test scenario) still working?

[st3iny]

Tested and works (in Mail).