refactor: Create SigningDriver and CiDriver (#197)

This also includes a new `login` command. The signing and CI logic is now using the Driver trait system along with a new experimental sigstore signing driver. New static macros have also been created to make implementation management easier for `Command` usage and `Driver` trait implementation calls.

---------

Co-authored-by: xyny <60004820+xynydev@users.noreply.github.com>

template/templates/Containerfile.j2

@@ -38,7 +38,5 @@ RUN rm -fr /tmp/* /var/* && ostree container commit
 LABEL {{ blue_build_utils::constants::BUILD_ID_LABEL }}="{{ build_id }}"
 LABEL org.opencontainers.image.title="{{ recipe.name }}"
 LABEL org.opencontainers.image.description="{{ recipe.description }}"
-{%- if let Some(repo) = self::get_repo_url() %}
 LABEL org.opencontainers.image.source="{{ repo }}"
-{%- endif %}
 LABEL io.artifacthub.package.readme-url=https://raw.githubusercontent.com/blue-build/cli/main/README.md

template/templates/init/README.j2

@@ -0,0 +1,45 @@
+# {{ repo_name }} Image Repo
+
+See the [BlueBuild docs](https://blue-build.org/how-to/setup/) for quick setup instructions for setting up your own repository based on this template.
+
+After setup, it is recommended you update this README to describe your custom image.
+
+## Installation
+
+> **Warning**
+> [This is an experimental feature](https://www.fedoraproject.org/wiki/Changes/OstreeNativeContainerStable), try at your own discretion.
+
+To rebase an existing atomic Fedora installation to the latest build:
+
+- First rebase to the unsigned image, to get the proper signing keys and policies installed:
+  ```
+  rpm-ostree rebase ostree-unverified-registry:{{ registry }}/{{ repo_name }}/{{ image_name }}:latest
+  ```
+- Reboot to complete the rebase:
+  ```
+  systemctl reboot
+  ```
+- Then rebase to the signed image, like so:
+  ```
+  rpm-ostree rebase ostree-image-signed:docker://{{ registry }}/{{ repo_name }}/{{ image_name }}:latest
+  ```
+- Reboot again to complete the installation
+  ```
+  systemctl reboot
+  ```
+
+The `latest` tag will automatically point to the latest build. That build will still always use the Fedora version specified in `recipe.yml`, so you won't get accidentally updated to the next major version.
+
+## ISO
+
+If build on Fedora Atomic, you can generate an offline ISO with the instructions available [here](https://blue-build.org/learn/universal-blue/#fresh-install-from-an-iso). These ISOs cannot unfortunately be distributed on GitHub for free due to large sizes, so for public projects something else has to be used for hosting.
+
+## Verification
+
+These images are signed with [Sigstore](https://www.sigstore.dev/)'s [cosign](https://github.com/sigstore/cosign). You can verify the signature by downloading the `cosign.pub` file from this repo and running the following command:
+
+```bash
+cosign verify --key cosign.pub {{ registry }}/{{ repo_name }}/{{ image_name }}
+```
+
+Cloned from https://github.com/blue-build/template