Add "see details" icon opening a text area with extract from log to splash screen

[HenrikJannsen]

With click on the loading state at the splash screen we show the current detail state (e.g. "circuit_create" form tor logs). This is very hidden and it only shows the current details not the history. It would be better to get debug infos when startup fails when users can more clearly find the way how to access that by adding an icon and showing the past xxx lines of the log file in a text area. Should be rather small text font with scrollbar and limited height to not impact too much the design. The logs should be selectable/copyable.