Use MWLogger logging for legacy logging methods

Send wfDebug, wfDebugLog, wfLogDBError and wfLogDBError log messages to
the new MWLogger PSR-3 logger subsystem. Compatibility with the historic
logging operations of wfLogDBError are provided by MWLoggerLegacyLogger
and the MWLoggerLegacySpi logger factory.

Requires the MWLogger system introduced in I5c82299 and the Composer
managed libraries from Ie667944.

Change-Id: I1e5596d590144fbfdfd5f18bc42cf1ef0dbcac12