This moves the new pipeline's invoice generation to the billing bucket, under the 'invoices/yyyy-MM' subdirectory.
This also changes the invoice e-mail to use a multipart message that attaches the invoice to the e-mail, to guarantee the correct MIME type and download.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181746191
This closes the end-to-end billing pipeline, allowing us to share generated detail reports with registrars via Drive and e-mail the invoicing team a link to the generated invoice.
This also factors out the email configs from ICANN reporting into the common 'misc' config, since we'll likely need alert e-mails for future periodic tasks.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=180805972
