download() or fetch() without netrw

[saccarosium]

Problem

• No easy way to download a file, though both curl and libuv are available in all Nvim targets.
• :edit <uri> (example: :edit https://example.com/foo.txt) is dependent on netrw for no reason

Expected behavior

separate PRs:

• introduce something like vim.fetch() (vim.net.fetch() ? idk, look at Go, NodeJS, for precedent)
  • could use curl or vim.loop
• use it to implement :edit <uri> without netrw
• use it to implement spellfile download. Disabling netrw disables the spelling files download suggestion neovim/neovim#7189

Related

• "gx" (open URL in browser) without netrw neovim/neovim#23231
• Consider removing netrw in favor of dirvish neovim/neovim#4378

Use-cases in the wild

• https://github.com/3rd/image.nvim/blob/88e9693e188b8464b1c426aebb4389fd9db2fcbf/lua/image/image.lua#L393

original issue: neovim/neovim#23232