fix content type issue defaulting to octet-stream

[hugosolar]

Description of the Change

This PR ensures that the blob is being sent to the storage with the proper content type as we're experiencing issues with some containers defaulting the content type to application/octet-stream
With this fix, we're not leaving the default content type but sending the file content type directly to the createBlockBlob() function through the $options parameters

Fixes #210

How to test the Change

• Using the plugin, upload an image to the blob container
• Using Azure storage explores, verify the proper content type is being set in the blob container

Changelog Entry

Fixed - Ensure we send the proper content type when creating the Block Blob in the container.

Credits

@hugosolar

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.