We need to handle bundles properly in all the operations related to the store. Most of that should be ok already, but for sure we need to improve some details: - in the `register` command, give the option to register the name for a bundle. The idea is to provide a `--type` option that will allow the `charm` and `bundle` values (and possibly more in the future, like `stack`); this `--type` can be avoided if the project from where the command is issued can be identified as one or the other, otherwise it's mandatory. - in the `names` command, add a column with the type of the package. - in the `build` command, we should support a `metadata.yaml` not being there but a `bundle.yaml`: in that case just build a zip named `.bundle` with everything that is there (pretty much like we do for charms) but without building dependencies, or creating hooks/dispatch, etc. So in reality build will have two modes ("charm" and "bundle"), decided automatically after what is found in the project. Note also that some options are valid for the different modes (like `--from`) but others are not (like `--entrypoint`): in the latter cases we need to raise an error. - in the `upload` command, we need to rename current `--charm-file` to be `--file` (supporting both charm and bundle files), and improve what is automatically detected from the project where the command is issued (we can guess the name from a possible `metadata.yaml`, for example, but not from a `bundle.yaml`).