fix(api-builder): add a custom template for interface

before we were using the template for class which is wrong

tools/api-builder/angular.io-package/templates/interface.template.html

@@ -1 +1,73 @@
-{% extends 'class.template.html' %}
+{% include "lib/githubLinks.html" -%}
+{% include "lib/paramList.html" -%}
+{% extends 'layout/base.template.html' -%}
+
+{% block body %}
+include {$ relativePath(doc.path, '_util-fns') $}
+
+{% include "layout/_what-it-does.html" %}
+
+{% include "layout/_security-notes.html" %}
+
+{% include "layout/_deprecated-notes.html" %}
+
+{% include "layout/_how-to-use.html" %}
+
+div(layout="row" layout-xs="column" class="ng-cloak")
+  div(flex="20" flex-xs="100")
+    h2(class="h2-api-docs") Interface Overview
+  div(flex="80" flex-xs="100")
+    code(class="no-bg api-doc-code openParens") interface {$ doc.name $} {
+
+    {% if doc.members.length %}
+    div(layout="column")
+      {% for member in doc.members %}{% if not member.internal %}
+        pre(class="prettyprint no-bg-with-indent")
+          a(class="code-anchor" href="#{$ member.name $}-anchor")
+            code(class="code-background api-doc-code") {$ member.name | indent(6, false) | trim $}
+          code(class="api-doc-code") {$ paramList(member.parameters) | indent(8, false) | trim $}{$ returnType(member.returnType) $}
+      {% endif %}{% endfor %}
+    {% endif %}
+    p(class="selector endParens")
+      code(class="api-doc-code no-bg") }
+
+{% block additional %}
+{% endblock %}
+
+div(layout="row" layout-xs="column" class="row-margin ng-cloak")
+  div(flex="20" flex-xs="100")
+    h2(class="h2-api-docs") Interface Description
+  div(class="code-links" flex="80" flex-xs="100")
+    :marked
+    {%- if doc.description.length > 2 %}
+{$ doc.description | indentForMarkdown(6) | trimBlankLines $}
+    {% endif %}
+
+{% if doc.members.length %}
+div(layout="row" layout-xs="column" class="instance-members" class="row-margin ng-cloak")
+  div(flex="20" flex-xs="100")
+    h2(class="h2-api-docs") Interface Details
+  div(class="code-links" flex="80" flex-xs="100")
+    {% for member in doc.members %}{% if not member.internal %}
+    a(name="{$ member.name $}-anchor" class="anchor-offset")
+    pre(class="prettyprint no-bg" ng-class="{ 'anchor-focused': appCtrl.isApiDocMemberFocused('{$ member.name $}') }")
+      code(class="api-doc-code").
+        {$ member.name $}{$ paramList(member.parameters) | indent(8, false) | trim $}{$ returnType(member.returnType) $}
+
+    :marked
+      {%- if not member.notYetDocumented %}
+{$ member.description | indentForMarkdown(6) | replace('### Example', '') | replace('## Example', '') | replace('# Example', '') | trimBlankLines $}
+      {% endif -%}
+
+    {% if not loop.last %}
+    .hr(class="hr-margin")
+    {% endif %}
+
+  {% endif %}{% endfor %}
+{% endif %}
+
+p(class="location-badge").
+  exported from {@link {$ doc.moduleDoc.id $} {$doc.moduleDoc.id $} },
+  defined in {$ githubViewLink(doc) $}
+
+{% endblock %}