Add `serverless_compute_id` field to the config

[alexkh-db]

Changes

We propose adding a new serverless_compute_id attribute in the config that will be used to enable serverless compute in the downstream applications. The default value to enable serverless is serverless_compute_id = auto, other values might be used in the future if needed. Config doesn't have to validate the value in serverless_compute_id, this will be done in the downstream applications.

Tests

• [x] make test run locally
• [x] make fmt applied
• [ ] relevant integration tests applied

[pietern]

Discussion in #675.