string utils: add string_view split, update base64

src/base64.cpp

src/base64.h

src/ice_transport.cpp

src/ip_utils.cpp

src/jamidht/jamiaccount.cpp

src/jamidht/namedirectory.cpp

src/media/media_encoder.cpp

src/string_utils.h

test/unitTest/string_utils/testString_utils.cpp