Add support for more generic notification

This is a start to have different kinds of notifications. It is
possible to be notified via e-mail, matrix or gotify. It also extends
the current "periodic query" for due items by allowing notification
over different channels. A "generic periodic query" variant is added
as well.

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

@@ -0,0 +1,140 @@
+{-
+   Copyright 2020 Eike K. & Contributors
+
+   SPDX-License-Identifier: AGPL-3.0-or-later
+-}
+
+
+module Comp.NotificationMatrixForm exposing (Model, Msg, init, initWith, update, view)
+
+import Api.Model.NotificationMatrix exposing (NotificationMatrix)
+import Comp.Basic as B
+import Data.NotificationChannel
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (onInput)
+import Messages.Comp.NotificationMatrixForm exposing (Texts)
+import Styles as S
+
+
+type alias Model =
+    { hook : NotificationMatrix
+    }
+
+
+init : Model
+init =
+    { hook = Data.NotificationChannel.setTypeMatrix Api.Model.NotificationMatrix.empty
+    }
+
+
+initWith : NotificationMatrix -> Model
+initWith hook =
+    { hook = Data.NotificationChannel.setTypeMatrix hook
+    }
+
+
+type Msg
+    = SetHomeServer String
+    | SetRoomId String
+    | SetAccessKey String
+
+
+
+--- Update
+
+
+update : Msg -> Model -> ( Model, Maybe NotificationMatrix )
+update msg model =
+    let
+        newHook =
+            updateHook msg model.hook
+    in
+    ( { model | hook = newHook }, check newHook )
+
+
+check : NotificationMatrix -> Maybe NotificationMatrix
+check hook =
+    Just hook
+
+
+updateHook : Msg -> NotificationMatrix -> NotificationMatrix
+updateHook msg hook =
+    case msg of
+        SetHomeServer s ->
+            { hook | homeServer = s }
+
+        SetRoomId s ->
+            { hook | roomId = s }
+
+        SetAccessKey s ->
+            { hook | accessToken = s }
+
+
+
+--- View
+
+
+view : Texts -> Model -> Html Msg
+view texts model =
+    div []
+        [ div
+            [ class "mb-2"
+            ]
+            [ label
+                [ for "homeserver"
+                , class S.inputLabel
+                ]
+                [ text texts.homeServer
+                , B.inputRequired
+                ]
+            , input
+                [ type_ "text"
+                , onInput SetHomeServer
+                , placeholder texts.homeServer
+                , value model.hook.homeServer
+                , name "homeserver"
+                , class S.textInput
+                ]
+                []
+            ]
+        , div
+            [ class "mb-2"
+            ]
+            [ label
+                [ for "roomid"
+                , class S.inputLabel
+                ]
+                [ text texts.roomId
+                , B.inputRequired
+                ]
+            , input
+                [ type_ "text"
+                , onInput SetRoomId
+                , placeholder texts.roomId
+                , value model.hook.roomId
+                , name "roomid"
+                , class S.textInput
+                ]
+                []
+            ]
+        , div
+            [ class "mb-2"
+            ]
+            [ label
+                [ for "accesskey"
+                , class S.inputLabel
+                ]
+                [ text texts.accessKey
+                , B.inputRequired
+                ]
+            , textarea
+                [ onInput SetAccessKey
+                , placeholder texts.accessKey
+                , value model.hook.accessToken
+                , name "accesskey"
+                , class S.textAreaInput
+                ]
+                []
+            ]
+        ]