Add language links to switch between English and Spanish (#842)

* Add language links to gov banner

- align banners to site logo
- create Language component and snapshot test
- add Language component to GovBanner
- update namespace for betaBanner scss.d.ts file

* Update snapshots for each page

* Componentizes the GovBanner

- add styles
- add unit test
- token most styles to USWDS

* Add language icon and update snapshots

* Make language link text smaller

* Update total height of BetaBanner

* Add languageLink to scss.d.ts file

* Add language links to mobile

- add isDesktop prop to Language component
- refactors header links to a simple array
- update snapshots

* Add href value to language links

- update snapshots

* merge other PRs and add spanish links

- merge PR 817
- merge PR 794
- add spanish links for footer
- add diffEnEs.js to detect differences between two json files
- adds esNoBrackets.json
- update intl README

* Add government banner in spanish

* Add spanish content for About and Explore page

client/src/components/Language/__snapshots__/Language.test.tsx.snap

@@ -0,0 +1,22 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`rendering of the Language checks if component renders 1`] = `
+<DocumentFragment>
+  <div>
+    <img
+      alt="language icon for selecting language"
+      src="test-file-stub"
+    />
+    <a
+      href="#"
+    >
+      English
+    </a>
+    <a
+      href="#"
+    >
+      Español
+    </a>
+  </div>
+</DocumentFragment>
+`;