Use retryable HTTP requests for Vault API (#1375)

## Description

By default API requests will immediately fail. FGA endpoints are the
exception that use a wrapper to retry some failures. This adds Vault
paths to the same retry logic. It also adds `408` response codes to the
list of retryable codes - `408` is set by the SDK when
catching/rethrowing a [request
timeout](https://github.com/workos/workos-node/blob/main/src/common/net/fetch-client.ts#L251).

## Documentation

Does this require changes to the WorkOS Docs? E.g. the [API
Reference](https://workos.com/docs/reference) or code snippets need
updates.

```
[ ] Yes
```

If yes, link a related docs PR and add a docs maintainer as a reviewer.
Their approval is required.