Miscellaneous refactoring

Random collection of assorted "little things" that make either the code or development a bit better.

Highlight: when building Keysmith in debug mode (-DCMAKE_BUILD_TYPE=Debug, usually the default) you get QML debugging/profiling support now. Hopefully profiling will help fix performance issues related to the indicator animation in a "better" way.

This little trick may potentially also be useful for other KDE apps... feels like this should be standard somehow.