Determine 'content-type' from S3 location

[maciejwalkowiak]

:loudspeaker: Type of change

• [ ] Bugfix
• [ ] New feature
• [x] Enhancement
• [ ] Refactoring

:scroll: Description

Sets content type to files uploaded to S3.

Fixes gh-262 Closes gh-419

:bulb: Motivation and Context

419 rebased against 2.3.x

:pencil: Checklist

• [x] I reviewed submitted code
• [x] I added tests to verify changes
• [ ] I updated reference documentation to reflect the change
• [x] All tests passing
• [ ] No breaking changes