tooltips: Use <div> tags inside tooltip's inner content.

By replacing `<span>` tags with `<div>` tags inside the tooltip's inner
content we remove the redundancy of having to use break tags to
separate the tooltip's title and it's content.

We also replace any `<p>` tags with `<div>` tags for the following
reasons:

- Since what we want to achieve are just block elements in order to
avoid the break tags, using `<div>` tags provide use with a wider
scope of use cases.

- We don't want the pause, screen readers often introduce after reading
the contents of a paragraph.

- The `<p>` tag cannot contain tables and other block-level elements.

- The semantic meaning of the <p> tag doesn't apply to the commonly
used tooltip content.

web/templates/narrow_to_compose_recipients_tooltip.hbs

@@ -1,7 +1,7 @@
 <div>
-    <span>{{t 'Go to conversation' }}</span>
+    <div>{{t "Go to conversation"}}</div>
     {{#if display_current_view}}
-    <p class="narrow_to_compose_recipient_current_view_help tooltip-inner-content italic">{{display_current_view}}</p>
+        <div class="tooltip-inner-content italic">{{display_current_view}}</div>
     {{/if}}
 </div>
 {{tooltip_hotkey_hints "Ctrl" "."}}