Ability to delete last few messages / go to a checkpoint

### Feature summary

Ability to delete last few messages / go to a checkpoint

### What problem are you trying to solve?

In VSCode, you can go to a certain checkpoint and that will effectively delete later messages and restore your conversation from that point. It is a very useful feature as sometimes the conversation takes a detour and we want to go back without needing to start a new one.

### Proposed solution

Follow what's been done in VSCode. Understandably, here we don't want to revert code, just move back to a certain point in conversation.

### Workflow impact

_No response_

### Installation context

_No response_

### Additional context

_No response_