Provide a "reset" command, so users can quickly be able to restart pgbelt migrations

[vjeeva]

Problem:

• Users encounter errors. Sometimes due to pgbelt bugs, sometimes due to dataset issues on their end, etc.
• Whenever any sort of issue occurs, they need to restart their migration jobs
• They can't just teardown and run setup again since data exists in their destination DBs.

Proposed Solution

• Provide a command like reset that can only work on a destination database.
• In full migrations, truncate all the destination tables, ensure sequences are set to 0, and ensure no FKs exist
• In exodus migrations, truncate all destination tables that are in the config, ensure sequences from the config are set to 0, and ensure no FKs exist in the tables from the config