feat(backupspec): extend manifest with info needed for tablet restore

To support tablet aware restore, we need to back up scylla manifests,
so we also need to keep track of them in manager manifest. Aside from
that, tablet aware restore works with tablet keyspaces only and with
scylla manifests starting from specific scylla version.

Fixes https://scylladb.atlassian.net/browse/CLOUD-267

Author: Michal-Leszczynski

backupspec/manifest.go

@@ -114,6 +114,7 @@ func (m *ManifestInfo) fileNameParser(v string) error {
 // ManifestContent is structure containing information about the backup.
 type ManifestContent struct {
 	Version         string          `json:"version"`
+	ScyllaVersion   string          `json:"scylla_version"`
 	ClusterName     string          `json:"cluster_name"`
 	IP              string          `json:"ip"`
 	Size            int64           `json:"size"`
@@ -282,6 +283,7 @@ func (m *ManifestContentWithIndex) ForEachIndexIter(keyspace []string, cb func(f
 }
 
 // ForEachIndexIterFiles performs an action for each filtered file in the index.
+// It targets just the FilesMeta.Files describing sstable components, but not FilesMeta.ScyllaManifests.
 func (m *ManifestContentWithIndex) ForEachIndexIterFiles(keyspace []string, mi *ManifestInfo, cb func(dir string, files []string)) error {
 	return m.ForEachIndexIter(keyspace, func(fm FilesMeta) {
 		dir := RemoteSSTableVersionDir(mi.ClusterID, mi.DC, mi.NodeID, fm.Keyspace, fm.Table, fm.Version)
@@ -314,11 +316,19 @@ type FilesInfo struct {
 
 // FilesMeta contains information about SST files of particular keyspace/table.
 type FilesMeta struct {
-	Keyspace string   `json:"keyspace"`
-	Table    string   `json:"table"`
-	Version  string   `json:"version"`
-	Files    []string `json:"files"`
-	Size     int64    `json:"size"`
+	Keyspace string `json:"keyspace"`
+	Table    string `json:"table"`
+	// ReplicationType of keyspace.
+	// Either "vnodes" or "tablets".
+	ReplicationType string   `json:"replication_type"`
+	Version         string   `json:"version"`
+	Files           []string `json:"files"`
+	Size            int64    `json:"size"`
+	// ScyllaManifests created by scylla on snapshot.
+	// They are stored alongside the snapshot-ed sstables.
+	// To avoid name collisions, their file names are prepended
+	// with "tag_<snapshot_tag>_node_<node_ID>_" prefix.
+	ScyllaManifests []string `json:"scylla_manifests"`
 
 	Path string `json:"path,omitempty"`
 }