Serve raw files with the correct content types

[tslocum]

Resolves #8152.

This is an alternative implementation to the existing PR for this issue.

[silverwind]

I think this should be optional and default off for the sake of security. See #8152 (comment).

[tslocum]

Thanks @silverwind. PR updated.

[silverwind]

See #8152 (comment) for a better suggestion.

[tslocum]

While I can see merit in your suggestion, the changes in this PR could be explicitly enabled by users via a configuration option (as you originally suggested), with a warning stating the potential security implications. It would also coexist with custom content types when they are implemented (i.e., check custom content types before detecting a file's content type).

Closing because the scope of the solution has grown beyond my interest.