Escape more characters in URLs

[neongreen]

We escape =?& already, but we should also escape {}|\^~[]`" because those characters make it harder for users to paste our URLs into chat/Markdown/etc (the list is as per https://tools.ietf.org/html/rfc3986#section-2.4).

Those characters have to be escaped everywhere a regex is rendered in a URL – i.e. ?query, ?filePath and ?filter.