o.c.logging.ui: Use UI thread in ConsoleViewHandler

Tried to avoid deadlocks by reducing synchronization. Turns out that
MessageConsoleStream locks internally, which resulted in CAJ, FreeTTS
and UI thread blocking each other while trying to log: CAJ was first,
locking inside MessageConsoleStream, but could not proceed because the
actual writing to the console in the UI thread didn't happen while the
UI thread wanted to log as well.
Now ConsoleViewHandler moves all logging to the UI thread.