D1 migrations: Add a Command to Remove or Revert the Last Applied Migration

[srini-abhiram]

It would be helpful to have a built-in command in the D1 migration toolchain (e.g., via wrangler or SQL studio) that allows developers to safely revert or remove the last applied migration.

Currently, once a migration is applied in D1:

The migration is recorded in the d1_migrations table.

There is no official or safe CLI/API method to roll it back.

Reverting it manually involves writing reverse SQL, deleting rows from d1_migrations manually.

This process is error-prone and risky, especially during development when schema changes are frequent and experimental.

Note: I am happy to work on it, if someone has not yet started on it.