dnfparse: add support for dnf repos for overrides

[lzap]

This is just a rough idea, today I was testing how repo override for Satellite works, one needs to create a JSON file and pass it. But on a registered system (to Satellite), there is already a repo file that contains everything, so I thought it would be nice to allow passing it directly:

image-builder manifest qcow2 --distro rhel-10.1 --force-repo=file:///etc/yum.repos.d/redhat.repo

I created a tiny repofile parser that reads the format and detection - when the --force-repo is a local file (not directory), then it tries to parse it and uses the information to build the override. This generates a manifest:

{
...
                "sha256:ff7914961b7976be1d3444d5315a6e5fcf9cdbb45d4903ff72fb306739612ce0": {
                    "path": "Packages/l/libblkid-2.40.2-15.el10_1.x86_64.rpm",
                    "mirror": "091140efa994c49267d7a3107b5e97036b2dec07b6bcc71b738b078f1ea30a54"
                }
            },
            "options": {
                "mirrors": {
                    "091140efa994c49267d7a3107b5e97036b2dec07b6bcc71b738b078f1ea30a54": {
                        "url": "https://katello.routed.lan/pulp/content/Default_Organization/Library/content/dist/rhel10/$releasever/x86_64/baseos/os",
                        "type": "baseurl",
                        "secrets": {
                            "name": "org.osbuild.mtls"
                        }
                    },
                    "cddaec356806ced85d76d87435ca6457443fc53d97d3acbef5f142517f89a252": {
                        "url": "https://katello.routed.lan/pulp/content/Default_Organization/Library/content/dist/rhel10/$releasever/x86_64/appstream/os",
                        "type": "baseurl",
                        "secrets": {
                            "name": "org.osbuild.mtls"
                        }
                    }
                }
            }
        }
    }
}

However, I am getting an error when trying to build this. Not sure why, something is missing not sure what that is:

Traceback (most recent call last):
  File "/usr/bin/osbuild", line 33, in <module>
    sys.exit(load_entry_point('osbuild==176', 'console_scripts', 'osbuild')())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osbuild/main_cli.py", line 187, in osbuild_cli
    manifest.download(object_store, monitor)
  File "/usr/lib/python3.12/site-packages/osbuild/pipeline.py", line 581, in download
    raise e
  File "/usr/lib/python3.12/site-packages/osbuild/pipeline.py", line 576, in download
    source.download(mgr, store)
  File "/usr/lib/python3.12/site-packages/osbuild/sources.py", line 40, in download
    reply = client.call("download", args)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osbuild/host.py", line 348, in call
    ret, _ = self.call_with_fds(method, args)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osbuild/host.py", line 384, in call_with_fds
    raise error
osbuild.host.RemoteError: RuntimeError: mtls secrets required but key (None) or cert (None) not defined
   File "/usr/lib/python3.12/site-packages/osbuild/host.py", line 268, in serve
    reply, reply_fds = self._handle_message(msg, fds)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osbuild/host.py", line 301, in _handle_message
    ret, fds = self.dispatch(name, args, fds)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osbuild/sources.py", line 106, in dispatch
    self.fetch_all(args["items"])
  File "/usr/lib/osbuild/sources/org.osbuild.librepo", line 259, in fetch_all
    self._setup_mtls(handle)
  File "/usr/lib/osbuild/sources/org.osbuild.librepo", line 167, in _setup_mtls
    raise RuntimeError(f"mtls secrets required but key ({key}) or cert ({cert}) not defined")