Add AccountMigrationManager with OTP accounts import and export methods #349

Job	Run time
Build and test / build-and-test	13m 1s
Prepare device farm artifacts / prepare-device-farm-artifacts	6m 28s
Run e2e tests in BitBar / bitbar-run	36s
Wait for and publish BitBar test results / bitbar-results	9m 9s
	29m 14s

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