Resolve "Translate login pages"

What does this MR do?

• Adds translations to the complete login page for both Admins as Guests.
• Changes the error on invalid token from Invalid Username and Password to Invalid Token to reflect guest's actions.
• Changes Enter on guest login page to Log in to match button clicked to get on the page: Log in as guest
• Changes Login to Log in on numerous places on the login pages. See

This MR splits the slogan into two separate key-value pairs. This might be considered unwanted. There are a few options to allow for line breaks in KV-pairs. (See here) I have chosen for this option because of it's readability. Another option was th:utext, but I felt like this one liner required too much explanation for what it was supposed to do The final option was to create a custom dialect. While this could be looked into in in the future, I also considered this to be too much code to make text appear on two lines as well as out of scope for this MR. EDIT The page header uses the first part of the slogan, thus this splitting might be necessary after all.

closes #118 (closed)

Screenshots

before

after

Does this MR meet the acceptance criteria?

• I have added tests to validate the new functionality.
• I have updated the documentation accordingly.
• I have added translations for all new client-side text.