Add daily credentials verification workflow (#3314)

## Motivation and Context
Adds a daily credentials verification workflow

## Description
We rotate credentials manually. Those credentials are
`RELEASE_AUTOMATION_BOT_CRATESIO_TOKEN` and
`RELEASE_AUTOMATION_BOT_PAT`. While the validity of those credentials
are checked during dry-runs of [the release
workflow](https://github.com/smithy-lang/smithy-rs/blob/main/.github/workflows/release.yml)
we've had instances where a dry-run failed because it was not idempotent
and we nevertheless kicked off a production run, only to find out the
token was invalid. This raises the need for daily credentials
verification, and the PR adds one.

The workflow will check the validly of two credentials
`RELEASE_AUTOMATION_BOT_CRATESIO_TOKEN` and
`RELEASE_AUTOMATION_BOT_PAT`, each checked by a separate job. Upon
failure, a job will notify us as follows:

<img width="1056" alt="Screenshot 2023-12-12 at 6 26 40 PM"
src="https://github.com/smithy-lang/smithy-rs/assets/15333866/1105b26b-7064-4ba2-849a-5969d59f1dd4">

## Testing
Manually triggered failures and got the messages in the above
screenshot. Also verified a successful run with valid credentials.

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