[11.x] Fix: Prevent invalid AWS credentials options being created

[robchett]

Improves on 909ea24 which could create credentials arrays with only a token

[taylorotwell]

Hey Robert! Can you elaborate a bit on this one? What is the problem with the current code? We use this logic quite a bit with Vapor so just want to make sure we aren't breaking something here.

Please mark as ready for review when you respond so I see it again.

[robchett]

An upstream bug in https://github.com/brefphp/laravel-bridge was causing credentials to be generated for AWS services with just a token and no key/secret. It's fixed here: brefphp/laravel-bridge#165, however I thought it would be good to prevent it in the Laravel source as well.

Only the code on src/Illuminate/Filesystem/FilesystemManager.php and src/Illuminate/Cache/CacheManager.php is incorrect in their current behaviour, the others are updated for consistency.

If preferred I can remove the changes to:

• src/Illuminate/Bus/BusServiceProvider.php
• src/Illuminate/Mail/MailManager.php
• src/Illuminate/Queue/Connectors/SqsConnector.php
• src/Illuminate/Queue/QueueServiceProvider.php