style: reformat C/C++ sources and headers with clang-format

Run clang-format over all project C/C++ source and header files
(.c, .cpp, .cc, .h, .hpp, .hh, .m, .mm) under app/ and tests/.
Non-source files (svg, qm, qrc, etc.) were not touched.

tests/gtest/audio_level_meter_test.cpp

@@ -11,7 +11,8 @@ extern "C" {
 #include <libavutil/channel_layout.h>
 }
 
-namespace {
+namespace
+{
 
 olive::core::AudioParams MakeStereoParams()
 {