Add ansible filetype detection

Based on 86eea3d684

templates/nvim/init.lua.j2

@@ -1,6 +1,8 @@
 -- {{ ansible_managed }}
 
+-- TODO: load environment vars from .env files
 require('options')
+require('_filetype')
 require('colorscheme')
 require('lsp')
 require('tree-sitter')