UI2: fix font metrics

[matejcik]

display_text_render accepts the coordinates of the baseline, i.e., is allowed to render below the provided y coordinate.

TextLayout renderer is calculating its cursor position based on text_height only, i.e., it will also render below its bounds and waste the baseline worth of space on the top.
While the fix looks easy in code (subtract baseline from the cursor y), this will shift pretty much all the text everywhere, so the impact will be far reaching.

On a similar note, we mostly use reported text_height, but it turns out that some characters are actually taller. We should be using calculated text_max_height for purposes of bounds fitting.