run-migrations: include details from Postgres errors

[alxndrsn]

Noticed while working on #1363.

Currently, when a postgres error has additional details, run-migrations.js will swallow these details.

Example

migration

module.exports = {
  down: () => {},
  up: db => db.raw(`
    INSERT INTO config (key) VALUES('a');
    INSERT INTO config (key) VALUES('a');
  `),
}

logging - master

Error: INSERT INTO config (key) VALUES('a'); INSERT INTO config (key) VALUES('a') - duplicate key value violates unique constraint "config_pkey"

logging - this PR

Error: INSERT INTO config (key) VALUES('a'); INSERT INTO config (key) VALUES('a') - duplicate key value violates unique constraint "config_pkey" (Key (key)=(a) already exists.)

---

What has been done to verify that this works as intended?

Tested locally.

Why is this the best possible solution? Were any other approaches considered?

This can make narrowing down specific problems with migrations easier if the thrown error contains a .detail.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

Should not affect users.

Does this change require updates to the API documentation? If so, please update docs/api.yaml as part of this PR.

Should not required documentation updates.

Before submitting this PR, please make sure you have:

• run make test and confirmed all checks still pass OR confirm CircleCI build passes
• verified that any code from external sources are properly credited in comments or that everything is internally sourced