Static Deploy to Github Pages (#73)

Addresses #58 , "As a member of the public, I want to see J40's website live on the internet, so that I know it's real!" - hosting on github pages for now as a temporary measure. This fix does NOT: 1) add .gov domain hosting, or 2) post to the geoplatform s3 bucket. This will need to happen in a subsequent fix. 

The changes made specifically to enable this for now:
* Adding github action to build, test, and deploy on pushes to client/
* Adding path prefix to build gh-pages at https://usds.github.io/justice40-tool/
* (Temporarily) pointing to fix branch for trussworks to enable SSR building
* Removing the workaround for the above bug in gatsby-node.js
* Setting build target to be 14.x due to version number limitations
* Adding gh-pages dependency, deploy action for manual deploy
* Force renaming J40header -> J40Header and J40footer -> J40Footer due to Linux case sensitivity

client/src/components/J40Header.tsx

@@ -0,0 +1,25 @@
+import React from 'react';
+import { GovBanner, Header, Title, PrimaryNav } from '@trussworks/react-uswds';
+import { useIntl, Link } from "gatsby-plugin-intl"
+
+const headerLinks = [
+    <Link to="/">Home</Link>
+];
+
+const J40Header = () => {
+    const intl = useIntl()
+    const title = intl.formatMessage({ id: "71L0pp", defaultMessage:"Justice40", description:"Title of the project" });
+    return (
+        <>
+        <GovBanner />
+        <Header>
+            <Title>
+                {title}
+            </Title>
+            <PrimaryNav items={headerLinks}/>
+        </Header>
+        </>
+    );
+};
+
+export default J40Header;