feat(gmail): add gmail integration

packages/backend/src/apps/gmail/common/add-auth-header.js

@@ -0,0 +1,9 @@
+const addAuthHeader = ($, requestConfig) => {
+  if ($.auth.data?.accessToken) {
+    requestConfig.headers.Authorization = `${$.auth.data.tokenType} ${$.auth.data.accessToken}`;
+  }
+
+  return requestConfig;
+};
+
+export default addAuthHeader;

packages/backend/src/apps/gmail/common/auth-scope.js

@@ -0,0 +1,8 @@
+const authScope = [
+  'https://www.googleapis.com/auth/gmail.compose',
+  'https://www.googleapis.com/auth/gmail.modify',
+  'https://www.googleapis.com/auth/userinfo.email',
+  'https://www.googleapis.com/auth/userinfo.profile',
+];
+
+export default authScope;

packages/backend/src/apps/gmail/common/get-current-user.js

@@ -0,0 +1,8 @@
+const getCurrentUser = async ($) => {
+  const { data: currentUser } = await $.http.get(
+    'https://people.googleapis.com/v1/people/me?personFields=names,emailAddresses'
+  );
+  return currentUser;
+};
+
+export default getCurrentUser;