Fixed #9893 -- Filename could exceed max_length on a collision

Passing max_length argument into the Storage's save() and get_available_name() methods.
Rewriting get_available_name() so filenames do not exceed max_length when there is a collision.
Adding test for the case.
Perhaps you can link  SuspiciousFileOperation to SuspiciousOperation since it's a subclass of SuspiciousOperation?

```rst
:exc:`SuspiciousFileOperation <SuspiciousOperation>`
```