Support for extra HTTP headers in the Trino CLI

[mingenuity]

Hello, we'd like to be able to specify additional HTTP headers when using the Trino CLI, for example to include a header such as X-Trino-Routing-Group so that requests can be routed appropriately via Trino Gateway.

This appears to already be supported in various Trino client libraries (Python, JS, C#, etc.), and while we could create our own CLI wrapper around one of those libraries, it would be great if this were supported in the official CLI. If there's any concern around allowing arbitrary headers, just having the option to specify a --routing-group argument to set the X-Trino-Routing-Group header would be sufficient.

I noticed that there is already an open PR for this feature (#15826), however it hasn't been updated in almost a year. Just wanted to follow up on this and see if there are any plans to pick up where that PR left off, or to add support through a separate PR. Thank you!

[mingenuity]

#15826 was merged and therefore this issue is resolved. Thank you!