- replace credential_file with GmailClient in Processor and ProcessorBuilder
- update builder method to accept GmailClient
- update trash_messages and delete_messages methods to use GmailClient
- introduce execute flag to control actual execution of actions
- add set_execute method to modify the execute flag
- log warning message when execution is stopped for dry run
- check if the label exists in the mailbox before proceeding to trash or delete messages
- return an error if the label is not found, preventing further processing
- add `delete_messages` function to delete messages based on label and query
- add execute flag to processor struct to control the execution of deletion
- implements struct `Processor` to manage rules for trashing messages
- adds method `trash_messages` to list and trash messages with labels and queries
