"Private chat" header for direct chats

Also, auto-create account and room when joining a DM chat link.

src/components/DirectChatWelcomeHeader.vue

@@ -0,0 +1,72 @@
+<template>
+  <div style="text-align: center;">
+  <div class="created-room-welcome-header">
+    <v-avatar class="typing-user" size="40" color="grey" v-if="isPrivate">
+          <img v-if="privatePartyAvatar(80)" :src="privatePartyAvatar(80)" />
+          <span v-else class="white--text headline">{{
+            privateParty.name.substring(0, 1).toUpperCase()
+        }}</span>
+    </v-avatar>
+    <h2>{{ $t("room_welcome.direct_hi") }}</h2>
+    <div class="mt-2" v-if="privateParty">{{ $t("room_welcome.direct_info", { user: privateParty.name }) }}</div>
+  </div>
+</div>
+</template>
+
+<script>
+import roomInfoMixin from "./roomInfoMixin";
+
+export default {
+  name: "CreatedRoomWelcomeHeader",
+  mixins: [roomInfoMixin],
+  computed: {
+    roomHistoryDescription() {
+      const visibility = this.$matrix.getRoomHistoryVisibility(this.room);
+      switch (visibility) {
+        case "world_readable":
+          return this.$t("room_welcome.room_history_is", {
+            type: this.$t("message.room_history_world_readable"),
+          });
+        case "shared":
+          return this.$t("room_welcome.room_history_is", {
+            type: this.$t("message.room_history_shared"),
+          });
+        case "invited":
+          return this.$t("room_welcome.room_history_is", {
+            type: this.$t("message.room_history_invited"),
+          });
+        case "joined":
+          return this.$t("room_welcome.room_history_joined");
+      }
+      return null;
+    },
+  },
+  data() {
+    return {
+      publicRoomLinkCopied: false
+    }
+  },
+  methods: {
+    copyPublicLink() {
+      const self = this;
+      this.$copyText(this.publicRoomLink).then(
+        function (ignored) {
+          // Success!
+          self.publicRoomLinkCopied = true;
+          setInterval(() => {
+            // Hide again
+            self.publicRoomLinkCopied = false;
+          }, 3000);
+        },
+        function (e) {
+          console.log(e);
+        }
+      );
+    }
+  }
+};
+</script>
+
+<style lang="scss">
+@import "@/assets/css/chat.scss";
+</style>