Create opt-in system for recent-messages

[RAnders00]

Is your feature request related to a problem? Please describe.
I'm trying to make my recent_messages service more compliant with the law, and i'd like more users to know about the optout options they have if they need them

Describe the solution you'd like
A section in the installer where the user is shown

• that Chatterino2 can fetch messages from the recent_messages service
• it will send each channel name you visit to a third-party service for that,
• and that channels you visit will have their messages stored
• that you can opt out of having the bot collect messages in your own channel by visiting https://recent-messages.robotty.de/ (Could be dynamic based on the recent messages url environment variable that was introduced), and that you can read the privacy policy by visiting that page
• Two buttons at the bottom "Accept terms and use service", "Decline terms and don't use service" (or something like that)

Describe alternatives you've considered
Don't do it i guess, but it would be nice, also to keep the users more informed

Additional context

[RAnders00]

Sorry, due to the rewrite of recent-messages the information is not quite accurate anymore. I'll work on updating this issue if somebody says they would be willing to even implement it.

[Mm2PL]

I can implement it :-)

[RAnders00]

@Mm2PL the privacy page has been reinstated. https://recent-messages.robotty.de/privacy You can go ahead with implementing the feature now.

[Mm2PL]

Maybe this could be done by inserting a system message with the question and two links: Accept and load history and Decline and don't ask again. I imagine this would look similar to automod allow/deny mod messages. Would probably require #1308. 🤔

[RAnders00]

Oh yeah, that‘s a neat idea for a solution that‘s low-friction for the user.