[renamerOnUpdate] Refactoring + cleanup

[bnkai]

Refactoring of the code to make it easier to maintain

• No functionality was changed/removed and no config options either so it should work withought any changes to existing config
• Only new addition atm is making the bulk processing work by batches

Renamer plugin and sqlite renamer script were removed as they were obsolete and all their functionality was moved to renamerOnUpdate anyway