[IMP] web: add pager widget to web client

This pager is used by the kanban view. It could be used by the list
view, the form view and some others (and it is, in the enterprise
edition)

addons/web/static/src/xml/base.xml

@@ -1946,6 +1946,15 @@
     <img t-attf-src="#{prefix}/web/static/src/img/icons/#{widget.icon}.png"
     t-att-alt="widget.string"/>
 </button>
+
+<div t-name="Pager">
+    <span class="o-pager-value"></span>
+    <span class="btn-group btn-group-sm">
+        <button type="button" class="fa fa-chevron-left btn btn-icon o-pager-previous" accesskey="O"/>
+        <button type="button" class="fa fa-chevron-right btn btn-icon o-pager-next" accesskey="P"/>
+    </span>
+</div>
+
 <button t-name="FieldToggleBoolean" type="button"
     t-att-title="widget.string" class="oe_toggle_button">
     <img t-attf-src="#{_s}/web/static/src/img/icons/#{widget.icon}" t-att-alt="widget.string"/>