Convert quiche_command_line_flags_impl.h over to the new-style #include path.

PiperOrigin-RevId: 439415161
diff --git a/common/platform/api/quiche_command_line_flags.h b/common/platform/api/quiche_command_line_flags.h
index 3ba48bb..783dea6 100644
--- a/common/platform/api/quiche_command_line_flags.h
+++ b/common/platform/api/quiche_command_line_flags.h
@@ -8,7 +8,7 @@
 #include <string>
 #include <vector>
 
-#include "net/quiche/common/platform/impl/quiche_command_line_flags_impl.h"
+#include "quiche_platform_impl/quiche_command_line_flags_impl.h"
 
 // Define a command-line flag that can be automatically set via
 // QuicheParseCommandLineFlags().