Trusted Header Authentication

Is your feature request related to a problem?

This is related to #1188, but the solution provided in the enterprise plan is much more enterprise oriented and does not meet some of the needs that I have or that others voiced in that ticket. It would be nice to support simple trusted header auth (like what Authelia provides) without having to go to the SigNoz login page. I implemented all of the code already and don't want to maintain my own separate fork and thought other self hosters that don't have the extra cash to spare on an enterprise plan like myself could benefit. This functionality is not currently in any enterprise plan and it would serves a hobbyist need rather than the more organizational focused needs provided in the enterprise plan.

Describe the solution you'd like

Allow for simple trusted header login without showing the login page configured with environment variables (no GUI needed). This solution is already mostly implemented and working on my local dev machine.

Describe alternatives you've considered

Paying for an enterprise plan (I'm poor and doesn't meet my needs).
Maintaining my own fork :(
Opening up a self-hosted hobbyist SigNoz instance to the world wide web. I don't like having many different username/passwords on many different logins across my services. Also I like to protect all my services behind a more security focused trustworthy gateway as I have seen multiple 0-days occur with services I have run where having them under one single roof has prevented my home lab from getting hacked. Additionally, it is easier for people who don't keep up with movements in the security world and limited time to be pedantic about keeping one important auth service up to date rather than everything.
Having 2 login pages. Really annoying

Thank you guys for this project! I am loving it so far!

SigNoz / signoz