Make the tablet tester dialogue translatable

For the non-mouse events, special care had to be taken to avoid ‘word puzzles’. The translator can specify how the device and action strings should be combined, so that, e.g., the two strings ‘Stylus’ + ‘release’, which are combinted into ‘Stylus release:’ in English, can have a different word order in the translation, e.g. ‘Release of Stylus:’ or ‘Stylus – release:’.

Test Plan

The actual tablet tester are in ‘Settings → Configure Krita → Tablet Settings → Open Tablet Tester’, but to really test it, you’ll have to translate Krita. :)

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.