Check mime type of attachment

[latin-panda]

What feature do you want to improve?
Medic Conf has some actions (upload-branding, upload-resources, upload-partners, etc) that uses a common library to get attachments and validates it's MIME Type. The MIME type checking got improved here by removing the hard coded types and use a library to do a more reliable checking.

Describe the improvement you'd like
Some actions might have special considerations which some types are only allowed. For example: upload-partners only upload images types, but not json files, upload-branding uploads images and also .ico type.
We might need to identify each action that uses attachment, determine the file types it needs and add specific MIME Type checking to present a warning if there's an invalid type uploaded.

Describe alternatives you've considered
Possibly pass a list of allowed MIME Types from the action definition to the attachment library and allow the library make the checking.