Hide context link for non-time-based index patterns

The link is hidden for index patterns that do not have a time field
defined, because the entry context view is designed to allow viewing the
surrounding entries with respect to a time ordering.

src/ui/public/doc_table/components/table_row/details.html

@@ -3,6 +3,7 @@
     <a
       class="btn btn-default btn-xs documentTableRow__action"
       ng-href="{{ getContextAppHref() }}"
+      ng-if="indexPattern.hasTimeField()"
     >
       <i class="fa fa-files-o" />
       View surrounding entries