[#727] util: Add MkdirAllX func

Add `MkdirAllX` function that wraps `os.MkdirAll`
and adds `x` permission for user and group.
This is used to make all created dirs openable
for user and group regardless of the read config
permissions.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

pkg/util/os.go

@@ -0,0 +1,10 @@
+package util
+
+import "os"
+
+// MkdirAllX calls os.MkdirAll with passed permissions
+// but with +x for user and group. This makes created
+// dir openable regardless of the passed permissions.
+func MkdirAllX(path string, perm os.FileMode) error {
+	return os.MkdirAll(path, perm|0110)
+}