Make channels unencrypted

Also, show info about older messages being deleted in rooms with message retention set.

src/components/welcome_headers/WelcomeHeaderChannelUser.vue

@@ -0,0 +1,37 @@
+<template>
+  <div class="created-room-welcome-header">
+    <div class="mt-2" v-if="roomMessageRetention() > 0">
+      <i18n path="room_welcome.info_retention_user" tag="span">
+        <template v-slot:time>
+          <b>{{ messageRetentionDisplay }}</b>
+        </template>
+      </i18n>
+    </div>
+  </div>
+</template>
+
+<script>
+import roomInfoMixin from "../roomInfoMixin";
+
+export default {
+  name: "WelcomeHeaderChannelUser",
+  mixins: [roomInfoMixin],
+  components: {
+  },
+  computed: {
+  },
+  data() {
+    return {
+    }
+  },
+  methods: {
+    onMessageRetention(ignoredretention) {
+      this.updateMessageRetention();
+    },
+  }
+};
+</script>
+
+<style lang="scss">
+@import "@/assets/css/chat.scss";
+</style>