shipjs prepare --retry

`--retry`

It prepares a PR for the latest version again.
It can be used when `shipjs trigger` somehow fails on CI, you add commits to fix it, and want to prepare a PR again.

It does the following extra things:

- Automatically uses the latest version. (Don't ask about next version)
- Delete local and remote branches: `releases/vx.y.z`
- Delete local and remote tag if exists.

Start at the implementation and entry point for `shipjs prepare`, then compare its flow with `shipjs trigger`; the issue names no files or tests. Done means `prepare --retry` reuses the latest version without prompting, removes local and remote `releases/vx.y.z` branches, and removes an existing local and remote tag.

Written by the indexing model from the issue text.