common/harnessLog was not ideally suited for general testing and made all the tests quite awkward. Instead, move all code used to test the common/log module into the logTest module and repurpose common/harnessLog to do log expect testing for all other tests in a cleaner way.
Add a few exceptions for config testing since the log levels are reset by default in config/parse.
This is more efficient overall and allows the caller to specify how many bytes will be read on each call. Reads are appended if the buffer already contains data but the buffer size will never increase.
Allow Buffer object "used size" to be different than "allocated size". Add functions to manage used size and remaining size and update automatically when possible.
Low-level functions only include stack trace in test builds while higher-level functions ship with stack trace built-in. Stack traces include all parameters passed to the function but production builds only create the parameter list when the log level is set high enough, i.e. debug or trace depending on the function.
