Add mock backend to support validating the output logs when
switching the log format at runtime. This removes the need to use
harness console when ztest framework is in use.
Fixes#47077
Signed-off-by: Aastha Grover <aastha.grover@intel.com>
Adding testcases for switching of logging formats at runtime.
Includes testing for log_backend_format_set,
log_format_set_all_active_backends & log_format_func_t_get
routines.
Signed-off-by: Aastha Grover <aastha.grover@intel.com>