feat: set up Button variant migration#455

haoruikun-cb wants to merge 6 commits intocds-v9coinbase/cds:cds-v9from

harryhao/cds-1613-create-migrator-to-map-button-variant-tertiary-to-variantcoinbase/cds:harryhao/cds-1613-create-migrator-to-map-button-variant-tertiary-to-variantCopy head branch name to clipboard