add Vim-like URL support for opening remote files

[Ikos3k]

Usage

$ micro <url>
# or inside micro
> open <url>

Tested on:

Arch Linux (6.16.2-arch1-1)
go version go1.24.6 linux/amd64

Examples:

$ micro https://raw.githubusercontent.com/zyedidia/micro/refs/heads/master/Makefile
$ micro https://tools.suckless.org/dmenu/patches/numbers/dmenu-numbers-20220512-28fb3e2.diff

[Andriamanitra]

I don't think this feature is worth the added complexity, it's essentially trying to turn micro into HTTP/FTP client. I would be unpleasantly surprised to find out micro www.example.com downloads a web page instead of just editing a file called www.example.com.

And you can already do curl -L <url> | micro to achieve the same thing.