Grafana Assistant: Amazon Athena support

<!-- Please only use this template for submitting feature requests --> **Why is this needed**: The new Grafana Assistant mode is a game changer and it works really well with e.g. Google BigQuery. We have **500+** end user companies that would benefit greatly from this within their automotive telematics use cases - but **95%+ of them use Amazon Athena** Grafana data source (the rest using Google BigQuery or SQL Server). We believe that adding support for Athena should be relatively straightforward as the functionality is 99% similar to BigQuery. We therefore hope this will be added soon. **What would you like to be added**: Currently Grafana Assistant does not work with Amazon Athena at all for e.g. running queries and analyzing data - we would like it to be able to work with Athena in the same way that it can work with BigQuery today. **Who is this feature for?** We develop professional-grade IoT data loggers for use by engineers within the automotive industry, including many top tier OEM customers as per our [100+ case studies](https://www.csselectronics.com/pages/can-bus-data-logger-case-studies). One of the key software tools these end users deploy is Grafana dashboards via plug & play integrations across all the major cloud servers (Amazon, Google, Azure) using Amazon Athena, Google BigQuery or Azure Synapse to query data from huge data lakes stored in buckets/containers. See also our [Grafana blog post](https://grafana.com/blog/2024/09/13/how-to-visualize-vehicle-can-bus-data-with-the-amazon-athena-data-source-for-grafana/) on this topic. The engineers typically have highly domain-specific expertise, meaning they are not familiar with writing SQL queries or creating dashboards - so Grafana Assistant is a perfect fit for them. If Athena support can be added, we would be able to on-board hundreds of users onto this new functionality. <img width="1504" height="804" alt="Image" src="https://github.com/user-attachments/assets/bf45b864-cdf8-4aad-9185-91ad7e7824bc" /…