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

test/testkeys.c

@@ -16,8 +16,7 @@
 
 #include <SDL3/SDL.h>
 
-int
-main(int argc, char *argv[])
+int main(int argc, char *argv[])
 {
     SDL_Scancode scancode;
 
@@ -30,7 +29,7 @@ main(int argc, char *argv[])
     }
     for (scancode = 0; scancode < SDL_NUM_SCANCODES; ++scancode) {
         SDL_Log("Scancode #%d, \"%s\"\n", scancode,
-               SDL_GetScancodeName(scancode));
+                SDL_GetScancodeName(scancode));
     }
     SDL_Quit();
     return 0;