fetch: cache collected

This avoids recollecting the cache files over and over again.

For example, `dvc fetch` noop in `dvc-bench` went from ~30sec down to ~10sec
for me.

Next step is to also cache remote index, so we don't have to waste those
~10sec checking files in the remote.

Related https://github.com/iterative/dvc-data/pull/376

pyproject.toml

@@ -34,7 +34,7 @@ dependencies = [
     "configobj>=5.0.6",
     "distro>=1.3",
     "dpath<3,>=2.1.0",
-    "dvc-data>=1.5.0,<1.6.0",
+    "dvc-data>=1.6.1,<1.7.0",
     "dvc-http>=2.29.0",
     "dvc-render>=0.3.1,<1",
     "dvc-studio-client>=0.9.2,<1",