Add allowUseOfTasknameFromCacheFile to the ClientMapping. SubCommand doesn't have to know about command names.
Add validateOptions in purge cmd. Improve messages in purge cmd. Remove unnecessary imports.
Merge pull request #4233 from AndresTanasijczuk/purgecmd

Add validateOptions in purge cmd. Improve messages in purge cmd.
Allow USER input datasets to be read from global DBS. Allow phys0x DBS only for USER input dataset. Move the validation of DBS URLs (and aliases) to validateConfig.
Merge pull request #4239 from AndresTanasijczuk/allowGlobalDBSforUSER

Allow USER input datasets to be read from global DBS.
Merge pull request #4231 from AndresTanasijczuk/noRefsToCommandsInSubCommand

Add allowUseOfTasknameFromCacheFile to the ClientMapping. SubCommand doe...