Support for usernames that contain the @ symbol

[SaintRyoh]

Hello, I would like to use dadbod to connect to a MSSQL server that has usernames in the format "username@website.com". The connection url doesn't currently seem to support having multiple '@' characters. It looks like the parsing of the url is done on line 44 of url.vim.
let match = matchlist(url, scheme . '://\%(\([^@/:]*\):\=\([^@/]*\)@\)\=\(\[[[:xdigit:]:]\+\]\|[^:/;,]*\)\%(:\(\d\+\)\)\=\($\|/.*\)')
I don't mind working on this issue and making a pull request, but I'm unsure how/if you'd like to solve it.

thank you!

[tpope]

URLs already have a solution for this: %40.