Log migration per-query information in a structured format

What does this MR do?

During migration testing, log a json file per migration with details of the individual queries executed during that migration.

Specifically, this includes:

• The sql text of each query
• any bind parameters
• start time
• end time

This data will support gitlab-org/database-team/team-tasks#147 (closed), which needs per-query timing information to create charts of query runtimes over the course of the migration, and details of the query text and bind parameters to report on queries with anomalous runtimes for specific parameter choices.

Screenshots (strongly suggested)

Here's a log from a test migration done by the pipeline that doesn't have any bind parameters: 20210604233157-query-details.json

Here's one from a test migration that I wrote locally that has a few queries with bind parameters: 20210615154212-query-details.json

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

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