Resolve "Remove support for MySQL"

statistics/CMakeLists.txt

statistics/DatabaseStatisticsService.cpp

statistics/DatabaseStatisticsService.hpp

statistics/DatabaseStatisticsServiceFactory.cpp

statistics/DatabaseStatisticsServiceFactory.hpp

statistics/FileStatistics.cpp

statistics/FileStatistics.hpp

statistics/JsonStatisticsService.cpp

statistics/JsonStatisticsService.hpp

statistics/JsonStatisticsServiceFactory.hpp

statistics/MySQLStatisticsService.cpp

statistics/MySQLStatisticsService.hpp

statistics/MysqlStatisticsSchema.before_SQL.cpp

statistics/MysqlStatisticsSchema.hpp

statistics/Statistics.cpp

statistics/Statistics.hpp

statistics/StatisticsSaveCmd.cpp

statistics/StatisticsSaveCmd.hpp

statistics/StatisticsSaveCmdLineArgs.cpp

statistics/StatisticsSaveCmdLineArgs.hpp