[KV Feedback]: include or exclude keys from backup data

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### Type of feedback

Feature request

### Description

When enabling automatic backup to S3/Google Cloud Storage, being able to configure which data should be included/excluded in the backup could be helpful to avoid storing non-relevant data.

### Additional context

We currently use Deno KV both as a persistence and as a cache system. While we would like our persistence data to be backed up, we're not really interested in backing up cache data. All of our cache entries are prefixed with the key `["cache", ...]` so it would be easy for us to simply exclude keys starting with `cache` if such feature would be available.

Start by reading the Deno KV automatic backup flow for S3 and Google Cloud Storage. Compare the persistence and cache key patterns described in the issue, especially keys prefixed with ["cache", ...]. Done means the backup configuration can include or exclude the requested key groups without backing up excluded data.

Written by the indexing model from the issue text.