Auto merge of #2449 - Turbo87:template-only, r=locks

Convert a few components to template-only components

r? @locks

Author: bors

app/components/flash-message.hbs

@@ -1,3 +1,3 @@
-<p local-class="flash {{if this.message "shown"}}" data-test-flash-message ...attributes>
-  {{this.message}}
+<p local-class="flash {{if @message "shown"}}" data-test-flash-message ...attributes>
+  {{@message}}
 </p>

app/components/flash-message.js

@@ -3,7 +3,7 @@
     {{yield}}
   {{else}}
     <h1 local-class="heading">
-      {{svg-jar this.icon local-class="icon"}}
+      {{svg-jar (or @icon "crate") local-class="icon"}}
       {{@title}}
       {{#if @suffix}}
         <small local-class="suffix">{{@suffix}}</small>

app/components/page-header.hbs

@@ -0,0 +1 @@
+<a href={{@user.url}} title={{@user.login}} ...attributes>{{yield}}</a>