fix(config): add extra validation for supported locales
fix(config): add extra validation for supported locales

eoger/fxa-auth-server,eoger/fxa-auth-server,mozilla/fxa-auth-server,mozilla/fxa-auth-server,vladikoff/fxa-auth-mailer,mozilla/fxa-auth-server,eoger/fxa-auth-server,mozilla/fxa-auth-server,vladikoff/fxa-auth-mailer,eoger/fxa-auth-server,vladikoff/fxa-auth-mailer