Import API: Instrumentation and metrics

Context

As part of the gradual migration plan, the registry will expose a new route which will start the migration of a repository. This route will be used by rails, which will be responsible for coordinating the migration.

This new route will need to be instrumented to meet observability requirements.

Possible Metrics

• Migration rate (how many repositories were migrated across different timeframes);
• Migration duration;
• Percentage of migrated repositories vs. the ones left (forecast);
• Percentage of canceled/rescheduled migrations;