[wip] add delta

[buritica]

This PR is a work in progress to add Delta's flight tracking details, no code yet need to understand what @alii has in mind for other resolvers and differences in interfaces.

[buritica]

@alii pls checkout https://github.com/alii/flight-tracker/blob/5c13147589d2438ade91e9598573aa226361397b/doc/wip-delta/index.md and let me know any thoughts on how you'd like to tackle this and I can try to organize a PR for delta.

[alii]

Thanks for these findings. I suppose the way forward would be to replicate the steps in order that a device would do. I would say it is appropriate for a resolver to do many network requests