Fix rendering of newly added tag when tag sanitization is enabled server-side

When adding a new tag and the tag sanitation is enabled server-side (default), the tag gets sanitized server-side and stored but it is not refreshed in the Web UI.

How to reproduce:

• in the Web UI, add tag test tag (with a whitespace) to a document

Expected result: the tag testtag is displayed as it has been sanitized server-side.
Actual result: the tag test tag is displayed. Refreshing the page renders the actual tag testtag

The sanitized tag is returned in the response of the PUT HTTP request.