Feature: basic lz.n setup

[horriblename]

things maybe to do:

• integrate into extraPlugins instead of using a separate option

todo:

• vomit code into init.lua when lazy.enable = false
• doc: add lazy section in keymaps
• doc: recommend vim.lazy.plugins instead

bug:

• there's this stupid bug where if you give only one plugin it doesn't work, I'll fix it upstream later fixed

[horriblename]

moved to #407