First version of new ui based on tailwind

This drops fomantic-ui as css toolkit and introduces tailwindcss. With
tailwind there are no predefined components, but it's very easy to
create those. So customizing the look&feel is much simpler, most of
the time no additional css is needed.

This requires a complete rewrite of the markup + styles. Luckily all
logic can be kept as is. The now old ui is not removed, it is still
available by using a request header `Docspell-Ui` with a value of `1`
for the old ui and `2` for the new ui.

Another addition is "dev mode", where docspell serves assets with a
no-cache header, to disable browser caching. This makes developing a
lot easier.

modules/webapp/src/main/elm/Comp/FieldListSelect.elm

@@ -1,5 +1,12 @@
-module Comp.FieldListSelect exposing (..)
+module Comp.FieldListSelect exposing
+    ( Model
+    , Msg
+    , update
+    , view
+    , view2
+    )
 
+import Comp.MenuBar as MB
 import Data.Fields exposing (Field)
 import Html exposing (..)
 import Html.Attributes exposing (..)
@@ -67,3 +74,31 @@ fieldCheckbox selected field =
             , label [] [ text (Data.Fields.label field) ]
             ]
         ]
+
+
+
+--- View2
+
+
+view2 : String -> Model -> Html Msg
+view2 classes selected =
+    div
+        [ class "flex flex-col space-y-4 md:space-y-2"
+        , class classes
+        ]
+        (List.map (fieldCheckbox2 selected) Data.Fields.all)
+
+
+fieldCheckbox2 : Model -> Field -> Html Msg
+fieldCheckbox2 selected field =
+    let
+        isChecked =
+            List.member field selected
+    in
+    MB.viewItem <|
+        MB.Checkbox
+            { id = "field-toggle-" ++ Data.Fields.toString field
+            , value = isChecked
+            , tagger = \_ -> Toggle field
+            , label = Data.Fields.label field
+            }