Also fixes a bug where we didn't triangulate at all when the char
count didn't warrant the likely overhead of spinning up a
thread_pool.
And fix another bug where EDA_TEXT::GetRenderCache() wasn't using
the given font.
Also reverts using the cache for drawing-sheet text. The text
items are created from scratch from the data items each time
they're drawn, so there's never an existing cache to make use of.
Instead, we now check that the item is in the view, using a very
approximate bounding box generator (because even generating a
real bounding box shows up large in profiles).
And, lastly, fixes a bug where EndPos was never considered in
DS_DATA_ITEM::IsInsidePage().
Fixes https://gitlab.com/kicad/code/kicad/-/issues/14822
1) Move a bunch of std::map's to std::unordered_map to get constant-time
look-ups
2) Lengthen progress-reporting intervals to spend more time doing work
and less time talking about it
3) Reverse order of SHAPE_LINE_CHAINs in thermal intersection checks to
make (much) better use of bbox caches
4) Don't re-generate bboxes we already have
5) Fix some autos that weren't by reference (and were therefore copying
large datasets)
6) Rename delta progressDelta so it's easier to search for in future
7) Get rid of a few more autos (because I don't like them)
8) Pass large items to lambdas by reference
Fixes https://gitlab.com/kicad/code/kicad/issues/12130