pass context to Find / FindSnapshot

This allows proper interruption of restic while it searches for
snapshots or key files.

internal/repository/key.go

@@ -116,7 +116,7 @@ func SearchKey(ctx context.Context, s *Repository, password string, maxKeys int,
 	checked := 0
 
 	if len(keyHint) > 0 {
-		id, err := restic.Find(s.Backend(), restic.KeyFile, keyHint)
+		id, err := restic.Find(ctx, s.Backend(), restic.KeyFile, keyHint)
 
 		if err == nil {
 			key, err := OpenKey(ctx, s, id, password)

internal/repository/repository.go

@@ -72,8 +72,8 @@ func (r *Repository) UseCache(c *cache.Cache) {
 
 // PrefixLength returns the number of bytes required so that all prefixes of
 // all IDs of type t are unique.
-func (r *Repository) PrefixLength(t restic.FileType) (int, error) {
-	return restic.PrefixLength(r.be, t)
+func (r *Repository) PrefixLength(ctx context.Context, t restic.FileType) (int, error) {
+	return restic.PrefixLength(ctx, r.be, t)
 }
 
 // LoadAndDecrypt loads and decrypts the file with the given type and ID, using