Fix LFS register (it needs json not data)

Refactored the LFS Oid handling in its class of its own and
add a way to recheck all LFS handles (or re-register)

lib/git_exporter.py

@@ -6,6 +6,7 @@ import yaml
 from lib.binary import is_binary_or_large
 from lib.db import DB
 from lib.git import Git
+from lib.lfs_oid import LFSOid
 from lib.obs import OBS
 from lib.proxy_sha256 import ProxySHA256
 from lib.tree_builder import TreeBuilder
@@ -60,6 +61,8 @@ class GitExporter:
         return left_to_commit
 
     def export_as_git(self):
+        if os.getenv("CHECK_ALL_LFS"):
+            LFSOid.check_all(self.db, self.package)
         tree = TreeBuilder(self.db).build(self.project, self.package)
         flats = tree.as_flat_list()