GetLogger doesn't return the expected logger if empty library name is in the arguments

[ThomsonTan]

The below test currently fails, because when creating new Logger, library_name in InstrumentationScope is set to logger_name if the passed in library_name is empty, but this logic is not honored when doing equity test between loggers.

auto lp1 = Provider::GetLoggerProvider()->GetLogger("Logger1");
auto another_lp1 = Provider::GetLoggerProvider()->GetLogger("Logger1");

EXPECT_EQ(lp1, another_lp1);