Public Engagement Page (#1372)

* Add public engagement page

- modifies sitemap config
- creates PublicEvent component
- adds SVGs for dates
- all copy is in intl

* Add Public Engagement button to each page

- create new PublicEng component
- add to each page
- update snapshots
- modify CEJST and Meth page to give button more space

* Make mobile compliant and fix DOM validation error

- transform each <p>'s descendent into a <CollectionDescription>
- fix a mobile rendering issue with <Collection> library
- format registration links so they render on mobile
- update snapshots

* Add spacing to descriptions and fix links

* Add Gherkin tests for testing links

- all zoom links should be functional
- ensure all legacy tests, test the new page
- add data-cy tag for cypress
- update snapshots

* Refactor to pass accessibility on all pages

- update snapshots

* Correct registration links

* Make registration links into buttons

* Make new tag bold

* Update copy based on feedback from Corey

client/src/pages/__snapshots__/methodology.test.tsx.snap

@@ -276,11 +276,36 @@ exports[`rendering of the DatasetContainer checks if various text fields are vis
       class="grid-container-desktop-lg"
       data-testid="gridContainer"
     >
-      <h1>
-        Methodology
-      </h1>
+      <section
+        class="page-heading"
+      >
+        <h1>
+          Methodology
+        </h1>
+        <div>
+          <div>
+            <span
+              class="usa-tag"
+              data-testid="tag"
+            >
+              NEW
+            </span>
+          </div>
+          <a
+            href="/public-engagement"
+          >
+            <button
+              class="usa-button usa-button--icon"
+              data-testid="button"
+              type="button"
+            >
+              Public Engagement
+            </button>
+          </a>
+        </div>
+      </section>
       <div
-        class="grid-row grid-gap j40-mb-5"
+        class="grid-row grid-gap j40-mb5-mt3"
         data-testid="grid"
       >
         <div