logbox can be expensive

[Habbie]

sometimes we dump big blobs of JSON to the log. For the logger, those count as one line, and then the logbox gets "5 lines" which is actually a 1000 lines. It looks like wrapping/laying out/rendering this is very expensive for LVGL.

Observations:

• removing the state.dump(2) log line from UIDummy::update shaves minutes off of startup time (on Toon1)
• instead of that, making UILogBox::update do nothing has the same effect

The logbox should probably be hidden by default, perhaps with an icon that can tell you "something important just appeared in here". Further, maybe we should have a configurable loglevel for terminal output -and- one for the logbox.

[Habbie]

Updating to LVGL 9/master has caused truncation of multiline messages to the first line, which makes everything faster :D