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/Util/CustomField.elm

@@ -1,4 +1,9 @@
-module Util.CustomField exposing (nameOrLabel, renderValue, renderValue1)
+module Util.CustomField exposing
+    ( nameOrLabel
+    , renderValue
+    , renderValue1
+    , renderValue2
+    )
 
 import Api.Model.ItemFieldValue exposing (ItemFieldValue)
 import Data.CustomFieldType
@@ -52,3 +57,41 @@ renderValue1 classes tagger cv =
                 text cv.value
             ]
         ]
+
+
+renderValue2 : List ( String, Bool ) -> Maybe msg -> ItemFieldValue -> Html msg
+renderValue2 classes tagger cv =
+    let
+        renderBool =
+            if cv.value == "true" then
+                i [ class "fa fa-check" ] []
+
+            else
+                i [ class "fa fa-minus" ] []
+
+        el : List (Html msg) -> Html msg
+        el =
+            case tagger of
+                Just t ->
+                    a
+                        [ classList classes
+                        , onClick t
+                        , href "#"
+                        ]
+
+                Nothing ->
+                    div [ classList classes ]
+    in
+    el
+        [ Icons.customFieldTypeIconString2 "" cv.ftype
+        , span [ class "ml-1 mr-2" ]
+            [ nameOrLabel cv |> text
+            ]
+        , div [ class "detail" ]
+            [ if Data.CustomFieldType.fromString cv.ftype == Just Data.CustomFieldType.Boolean then
+                renderBool
+
+              else
+                text cv.value
+            ]
+        ]