clang-format: set BraceWrapping::AfterControlStatement to "MultiLine"

This was the code-style Blender used before switching to clang-format
which did not support this style of brace placement at the time.

Since then support was added, this helps readability as the beginning
of braces isn't as clear in the case of multi-line conditionals.

This implements a proposal from #75956.

.clang-format

@@ -62,7 +62,7 @@ ContinuationIndentWidth: 4
 BreakBeforeBraces: Custom
 BraceWrapping: {
     AfterClass: 'false',
-    AfterControlStatement: 'false',
+    AfterControlStatement: 'MultiLine',
     AfterEnum : 'false',
     AfterFunction : 'true',
     AfterNamespace : 'false',