Use the directory username to search for accounts when changing the email attribute

[mwilmes-at-avc]

Summary

• When the username is not changing, is not an email address, and the email attribute is different between the directory and umapi accounts, use the username as the lookup value for the umapi update command. Otherwise, continue to use the directory email address.

Testing Steps

user-sync-config.yml
connector-umapi.yml
connector-ldap.yml

• In a tenant with FereratedIDs, use the sync tool to create an account where the username is a non-email identifier.
• Update the directory source so that the email attribute is changed, but the identifier attribute is not.
• Rerun the sync tool to update the email address of the account.
  • The sync tool from the current codebase will fail, unable to find the account in Adobe using the new email address.
  • The sync tool with this patch will succeed by using the username attribute to update the account.

NOTE: This has worked against my production tenant. Project maintainers and Adobe employees may PM me with their GitHub handle if they need details about my tenant.

Fixes #827