Remove discord.com mentions and fix login screen CSS

[CE1CECL]

Having 2-3 .CSS files didn't work half the time at least for the login screen, the discord logo showed UNLESS you were at /login and refresh the page yourself. I also removed discord.com from the HTML file to null, b/c clicking on the badges took to discord.com, now it shouldn't (although during testing, changing them to something else change discord.com to what it was changed to, null was untested of this behavior tho) Also removed localhost mentions from HTML, since localhost:3003 was nothing to the client since that html was what was being sent out to the public, even discord.com doesn't use localhost for there assets (or at least not in HTML files). In fact, localhost:3003 didn't even exist, I could of changed 3003 from everything but I didn't want to change/break too much so I left it in case it would be used in the future. Last thing I changed was the requirement of the cdn public endpoint, it wasn't working when I opened it in a new tab, solved it by making it /attachments WITHOUT the hostname, since /xyz is the root of a domain of any browser for any website, if you get what I'm saying.

I also made fixes to css where it would say you need to accept instance agreement on every hover, and made invites as port numbers unless if http:80 and https:443, then no port will be there.

This is a improvement from https://github.com/fosscord/fosscord-server/pull/829 and goes into staging branch. I also had some hard time with putting master to staging in case you wanted to know why all the commits. I also re added erlpack b/c for some reason was removed. Files not used anymore are empty not deleted for compatibility. Last thing I did was that I reverted a patch that broke building fosscord.

Oh and those images are attached: