[19.0][fs_storage] Error 500 on direct attachment streaming

[arielbarreiros96]

Method _to_http_stream not overridden for attachments, it causes causes FileNotFoundError (HTTP 500) on direct attachment streaming

Module

fs_attachment

Bug

When the method _to_http_stream is called, for example when loading the /doc endpoint, there is a 500 error, and on the logs can be seen Traceback: ir_attachment.py:921 os.stat(stream.path) → FileNotFoundError: /var/lib/odoo/filestore/mydatabase/s3://my_s3_bucket.

This happens for example when S3 locations is being used, non detectable with regular filestore

To Reproduce

19.0
1- Completely configure S3 filestore
2- Try to access /doc endpoint

Notice that this is how I found out, any other call to _to_http_stream should cause the same problem

[arielbarreiros96]

Tested after the changes on #632 and now the /doc enpoint loads