Add dropdown to navigation links

- add download page
- move main pages tests to their own folder
- add download and public eng snapshot test
- remove public engagement button on each page
- swap index with cejst
- update cypress ENDPOINTS
- upate gatsby-config sitemap
- update snapshots
- cypress tests are failing

client/cypress/support/step_definitions/commonSteps.js

@@ -13,6 +13,11 @@ Given('I am on the {string} page', (page) => {
 });
 
 // Common Whens:
+When(`I click on the {string} dropdown in the navigation`, (page) => {
+  const pageHyphenCase = hyphenizeString(page);
+  cy.get(`[data-cy="nav-dropdown-${pageHyphenCase}"]`).click();
+});
+
 When(`I click on the {string} page in the navigation`, (page) => {
   const pageHyphenCase = hyphenizeString(page);
   cy.get(`[data-cy="nav-link-${pageHyphenCase}"]`).click();