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)

test/testrendertarget.c

@@ -24,7 +24,8 @@
 
 static SDLTest_CommonState *state;
 
-typedef struct {
+typedef struct
+{
     SDL_Window *window;
     SDL_Renderer *renderer;
     SDL_Texture *background;
@@ -172,8 +173,7 @@ Draw(DrawState *s)
     return SDL_TRUE;
 }
 
-void
-loop()
+void loop()
 {
     int i;
     SDL_Event event;
@@ -203,8 +203,7 @@ loop()
 #endif
 }
 
-int
-main(int argc, char *argv[])
+int main(int argc, char *argv[])
 {
     int i;
     int frames;
@@ -277,7 +276,7 @@ main(int argc, char *argv[])
     /* Print out some timing information */
     now = SDL_GetTicks();
     if (now > then) {
-        double fps = ((double) frames * 1000) / (now - then);
+        double fps = ((double)frames * 1000) / (now - then);
         SDL_Log("%2.2f frames per second\n", fps);
     }