♻️ Simplify Decryption Ceremony in CLI

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Suggestion

The CLI includes a [decrypt tally step](https://github.com/microsoft/electionguard-python/blob/main/src/electionguard_cli/e2e_steps/decrypt_step.py). This could take advantage of the Tally Ceremony Orchestrator to reduce down the duplicated code.

https://github.com/microsoft/electionguard-python/blob/8aa589c9744bdf52e1e2659e2f83c255ffc65441/src/electionguard_tools/helpers/tally_ceremony_orchestrator.py#L15

### Possible Implementation

_No response_

### Anything else?

Improvements to the Tally Ceremony Orchestrator including generating the Lagrange coefficients could be present here.