### What needs to get done * Add a new abstract method, `prune`, to the Provider class in craft-providers * Implement the method in LXDProvider to remove instances for a LXD project * If `prune_templates` is true, base instances should be removed too * Implement the method in MultipassProvider to purge all Multipass VMs for the application * `prune_templates` is ignored for the MultipassProvider since it doesn’t support base instances. * Integration and unit tests for both Multipass and LXD. The integration tests should: * Create multiple instances with different bases in that provider, run prune, and check that all of the relevant instances (but only those) were destroyed. This includes creating a separate “unmanaged” VM/container that we check is not destroyed. * Ensure that you do not delete managed instances from another application that uses craft-providers. (E.g. Snapcraft does not delete Charmcraft instances) ```py class Provider: @abstractmethod def prune(self, *, prune_templates: bool = False): class LXDProvider(Provider): def prune(self, *, prune_templates: bool = False): ... class MultipassProvider(Provider): def prune(self, *, prune_templates: bool = False): ... ``` ### Why it needs to get done To allow users to prune instances. Requires https://github.com/canonical/craft-providers/issues/639 Required for https://github.com/canonical/craft-application/issues/991 Required for https://github.com/canonical/charmcraft/issues/1042