feat: colrev-shell

[geritwagner]

Feature Request

CoLRev could offer an interactive shell (e.g., based on cmd2) as an interface (similar to the R-shell). A key benefit would be that the dataset (and settings) could be stored in memory during operations and that autocompletion (e.g., based on package endpoints) could be easier.

• Keep records as a variable (lazy-loading in dataset), to enable more efficient pipelines (without re-initializing the review_manager).
• Give users the option to activate automated triggering of the next operations (based on watchdog).
• Remove/integrate colrev/service.

Related: #56

[noriakisana]

• cmd
  • basic simple command input
  • suggest the next commands
• watchdog integration