Lazy luarocks support

[vhyrro]

This pull request moves Neorg away from using luarocks.nvim, preferring lazy's native luarocks support instead. This hugely simplifies the configuration and initial overhead required to make Neorg function on your average machine. This is a breaking change.

What the new configuration looks like (no dependencies required):

{
    "nvim-neorg/neorg",
    lazy = false,
    version = "*",
    config = true,
}

Big thanks to folke for the luarocks support :)