Enhance `cargo set-command` to support custom pre-release identifiers

The `cargo set-command` currently supports bumping pre-releases but is limited to specific values (rc, beta, alpha). However, the SemVer specification does not restrict pre-release identifiers to these specific values.

When using `cargo set-command` to bump pre-releases, only "rc", "beta", and "alpha" are accepted as valid identifiers.

I would like to propose allowing of custom pre-release identifiers beyond the current hardcoded set, making the command fully compliant with the [SemVer specification](https://semver.org/#spec-item-9) which allows any valid alphanumeric identifier. I am working on a project where `dev` is used as an identifier i.e `x.x.x-dev.x`

What do you think?

Start at the cargo set-command implementation and trace how pre-release identifiers are validated and passed to the version bump. Check the existing tests for rc, beta, and alpha behavior, then add coverage showing that a valid custom identifier such as dev is accepted while the command remains compliant with SemVer.

Written by the indexing model from the issue text.