rpmmd: add ignore_ssl to serialisable repo config

The internal repository configuration (RepoConfig) supports IgnoreSSL
which, when set to `true`, will run a depsolve job with the dnf repo
parameter `sslverify` set to `false`.

The serialisable repo object (repository) did not support reading this,
so it was impossible to set in global repo configs (from
/usr/share/osbuild-composer/repositories and
/etc/osbuild-composer/repositories).
It was, however, possible to set it through the weldr API when adding a
new source.

internal/rpmmd/repository.go

@@ -22,6 +22,7 @@ type repository struct {
 	MirrorList     string   `json:"mirrorlist,omitempty"`
 	GPGKey         string   `json:"gpgkey,omitempty"`
 	CheckGPG       bool     `json:"check_gpg,omitempty"`
+	IgnoreSSL      bool     `json:"ignore_ssl,omitempty"`
 	RHSM           bool     `json:"rhsm,omitempty"`
 	MetadataExpire string   `json:"metadata_expire,omitempty"`
 	ImageTypeTags  []string `json:"image_type_tags,omitempty"`