Add delay customization to tooltip.js

This MR allows the delay of tooltips instantiated using
tooltip.js to be customized through localStorage.

app/assets/javascripts/vue_shared/directives/tooltip.js

@@ -3,8 +3,12 @@ import '~/commons/bootstrap';
 
 export default {
   bind(el) {
+    const glTooltipDelay = localStorage.getItem('gl-tooltip-delay');
+    const delay = glTooltipDelay ? JSON.parse(glTooltipDelay) : 0;
+
     $(el).tooltip({
       trigger: 'hover',
+      delay,
     });
   },