This simplifies the API and removes a level of API translation between the int variants of the functions and the float implementation
Fixes https://github.com/libsdl-org/SDL/issues/6656
Feedback from @icculus:
"IsTablet" uses "is" as a form of "to be" ...like, the actual question is of its nature.
The rest is just a superfluous word in the question and it flows as better English with if (RectEmpty) than if (IsRectEmpty)
Fixes https://github.com/libsdl-org/SDL/issues/6932
I ran this script in the include directory:
```sh
sed -i '' -e 's,#include "\(SDL.*\)",#include <SDL3/\1>,' *.h
```
I ran this script in the src directory:
```sh
for i in ../include/SDL3/SDL*.h
do hdr=$(basename $i)
if [ x"$(echo $hdr | egrep 'SDL_main|SDL_name|SDL_test|SDL_syswm|SDL_opengl|SDL_egl|SDL_vulkan')" != x ]; then
find . -type f -exec sed -i '' -e 's,#include "\('$hdr'\)",#include <SDL3/\1>,' {} \;
else
find . -type f -exec sed -i '' -e '/#include "'$hdr'"/d' {} \;
fi
done
```
Fixes https://github.com/libsdl-org/SDL/issues/6575
