Migrate the ProxySHA256 data into postgresql DB

The calculation of the sha256 and the mimetype is local due to that

lib/hash.py

@@ -0,0 +1,20 @@
+import functools
+import hashlib
+
+
+def _hash(hash_alg, file_or_path):
+    h = hash_alg()
+
+    def __hash(f):
+        while chunk := f.read(1024 * 4):
+            h.update(chunk)
+
+    if hasattr(file_or_path, "read"):
+        __hash(file_or_path)
+    else:
+        with file_or_path.open("rb") as f:
+            __hash(f)
+    return h.hexdigest()
+
+
+md5 = functools.partial(_hash, hashlib.md5)