Send full form values to email signup endpoint (#191)

## Test Plan

Submit the form with an email filled out; look at network inspector to
make sure the new param is included and reflects the form value.

src/email-signup.ts

@@ -1,4 +1,5 @@
 import { safeLocalStorage } from './safe-local-storage';
+import { FormValues } from './state-calculator-form';
 
 const LOCAL_STORAGE_KEY = 'RA-calc-email-submitted';
 
@@ -15,8 +16,7 @@ export function wasEmailSubmitted(): boolean {
 export async function submitEmailSignup(
   apiHost: string,
   apiKey: string,
-  email: string,
-  zip: string,
+  formValues: FormValues,
   emailRequired: boolean,
 ): Promise<boolean> {
   safeLocalStorage.setItem(LOCAL_STORAGE_KEY, true);
@@ -27,7 +27,7 @@ export async function submitEmailSignup(
 
     const response = await fetch(url, {
       method: 'POST',
-      body: JSON.stringify({ email, zip, emailRequired }),
+      body: JSON.stringify({ ...formValues, emailRequired }),
       headers: {
         Authorization: `Bearer ${apiKey}`,
         'Content-Type': 'application/json',

src/state-calculator.tsx

@@ -170,9 +170,8 @@ const StateCalculator: FC<{
   const submit = (formValues: FormValues) => {
     safeLocalStorage.setItem(FORM_VALUES_LOCAL_STORAGE_KEY, formValues);
 
-    const email = formValues.email;
-    if (email && !emailSubmitted) {
-      submitEmailSignup(apiHost, apiKey, email, formValues.zip, emailRequired);
+    if (formValues.email && !emailSubmitted) {
+      submitEmailSignup(apiHost, apiKey, formValues, emailRequired);
       // This hides the email field
       setEmailSubmitted(true);
     }