Add an option to use Elite Insights as backend

[Sejsel]

This would make results consistent

This is also somewhat of a requirement to integrate with wingman (#126) without having to use dps.report along the way. dps.report is already expensive enough for Micca, who runs it, I really do not want to increase those costs just so people can upload to wingman.

Installing and updating Elite Insights

I am not yet 100% sure how installation and updates of Elite Insights will be handled. I am not a massive fan of automatic updates, as it would make it possible for a compromised account with release access to EI to deliver a malicious payload that would be executed. EI releases currently have no signatures, which would probably be enough to be reasonably secure. Maintaining a list of valid versions with signatures (as uploaded artifacts can be changed after release) is also out of question, EI releases are frequent and there is not enough manpower to maintain a list like this.

Downloading EI manually all the time would be inconvenient, I am leaning towards having a convenient button that installs it for you, prompts to update, but they really aren't that far off from automatic updates.