Add expected error/success messages to view tests

[timobrembeck]

Motivation

After #2454, it is now possible to view the user messages in the server logs in debug mode.

Proposed Solution

We could use this to further improve the view tests by adding a new "expected messages" column to the each entry in the view config.
E.g. for normal get-views, we could make sure that no error messages are present, or for form-submit-views we require the correct success message to exist.

Creating the initial baseline version for these kind of tests is probably very time consuming, maybe it's possible to somehow script this by inserting empty lists first and then extracting the actual messages from the failed tests?