Merge pull request #3522 from greatroar/dump-lru

Use LRU cache in restic dump

changelog/unreleased/pull-3508

@@ -0,0 +1,10 @@
+Enhancement: Cache blobs read by the dump command
+
+When dumping a file using the `restic dump` command, restic did not cache blobs
+in any way, so even consecutive runs of the same blob did get loaded from the
+repository again and again, slowing down the dump.
+
+Now, the caching mechanism already used by the `fuse` command is also used by
+the `dump` command. This makes dumping much faster, especially for sparse files.
+
+https://github.com/restic/restic/pull/3508