[Notes Applet] Reduce switch size and hide controls if too small

When resizing the applet smaller it can be unexpected that it suddenly switches to compact
representation, especially when formatting controls (Bold, etc) aren't shown.
Reduce the switch size to be quite small and just hide the formatting controls if the applet
becomes too small.
Nowadays you can toggle formatting with Ctrl keys (Ctrl+B for Bold, etc) anyway.
Also, move the formatting controls into their own Row so we can hide them as a single unit.

Differential Revision: https://phabricator.kde.org/D4069