Fix trailing whitespace and add pre-commit hook

Some have their editor configured to remove trailing whitespace and
editing such a file would "fix" it, adding an unrelated change.

Fix whitespace violations excluding third party libs and generated files
like glad or patches.

Enable pre-commit hook trailing-whitespace to enforce it in the future.

Fixes: #8016
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>

source/maths/MathUtil.h

@@ -41,7 +41,7 @@ inline T Clamp(T value, T min, T max)
 template<typename T>
 inline T SmoothStep(T edge0, T edge1, T value)
 {
-	value = Clamp<T>((value - edge0) / (edge1 - edge0), 0, 1); 
+	value = Clamp<T>((value - edge0) / (edge1 - edge0), 0, 1);
 	return value * value * (3 - 2 * value);
 }