core: rename mbgl namespace to mln (#4487)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

platform/android/src/timer.cpp

@@ -6,7 +6,7 @@
 #include <atomic>
 #include <functional>
 
-namespace mbgl {
+namespace mln {
 namespace util {
 
 class Timer::Impl : public RunLoop::Impl::Runnable {
@@ -74,4 +74,4 @@ void Timer::stop() {
 }
 
 } // namespace util
-} // namespace mbgl
+} // namespace mln