Update for SDL3 coding style (#6717)

I updated .clang-format and ran clang-format 14 over the src and test directories to standardize the code base.

In general I let clang-format have it's way, and added markup to prevent formatting of code that would break or be completely unreadable if formatted.

The script I ran for the src directory is added as build-scripts/clang-format-src.sh

This fixes:
#6592
#6593
#6594

(cherry picked from commit 5750bcb174)

src/main/dummy/SDL_dummy_main.c

@@ -8,15 +8,13 @@
 
 #ifdef main
 #undef main
-int
-main(int argc, char *argv[])
+int main(int argc, char *argv[])
 {
     return SDL_main(argc, argv);
 }
 #else
 /* Nothing to do on this platform */
-int
-SDL_main_stub_symbol(void)
+int SDL_main_stub_symbol(void)
 {
     return 0;
 }