maintenance(admin-panel): Stop formatting auto generated graphql code

Because:
- Saving the file results in a different default formatting.

This Commit:
- Adds prettier ignore statements so that the files don't get accidentally formated.

Closes: #

.prettierignore

@@ -1,2 +1,6 @@
 .yarn
 *.mjml
+
+# Autogenerated files
+packages/fxa-admin-server/src/schema.gql
+packages/fxa-admin-server/src/graphql.ts