cmd, restic: Refactor and fix snapshot filtering

This turns snapshotFilterOptions from cmd into a restic.SnapshotFilter
type and makes restic.FindFilteredSnapshot and FindFilteredSnapshots
methods on that type. This fixes #4211 by ensuring that hosts and paths
are named struct fields instead of unnamed function arguments in long
lists of such.

Timestamp limits are also included in the new type. To avoid too much
pointer handling, the convention is that time zero means no limit.
That's January 1st, year 1, 00:00 UTC, which is so unlikely a date that
we can sacrifice it for simpler code.

internal/fuse/root.go

@@ -16,9 +16,7 @@ import (
 // Config holds settings for the fuse mount.
 type Config struct {
 	OwnerIsRoot   bool
-	Hosts         []string
-	Tags          []restic.TagList
-	Paths         []string
+	Filter        restic.SnapshotFilter
 	TimeTemplate  string
 	PathTemplates []string
 }

internal/fuse/snapshots_dirstruct.go

@@ -295,7 +295,7 @@ func (d *SnapshotsDirStructure) updateSnapshots(ctx context.Context) error {
 	}
 
 	var snapshots restic.Snapshots
-	err := restic.FindFilteredSnapshots(ctx, d.root.repo.Backend(), d.root.repo, d.root.cfg.Hosts, d.root.cfg.Tags, d.root.cfg.Paths, nil, func(id string, sn *restic.Snapshot, err error) error {
+	err := d.root.cfg.Filter.FindAll(ctx, d.root.repo.Backend(), d.root.repo, nil, func(id string, sn *restic.Snapshot, err error) error {
 		if sn != nil {
 			snapshots = append(snapshots, sn)
 		}