Enhancement: Add `root_path` value to OpenAPI servers if present

Summary

Currently the OpenAPI config servers URLs default to "/" even if a root_path is present, even though for example debug errors display the root_path. (ValueError on GET /api/ if a ValueError is raised in test_handler in the code below.)

It would be nice to have Litestar automatically add the root_path value --if present-- as the default instead.

Basic Example

Code:

from litestar import Litestar, get, Request


@get(path="/", sync_to_thread=False)
def test_handler(request: Request) -> dict[str, str | list]:
    return {
        "request.scope['root_path']": request.scope["root_path"],
        "app.openapi_config.servers": request.app.openapi_config.servers,
    }


app = Litestar(route_handlers=[test_handler], debug=True)

if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, port=5000, root_path="/api")

Current response (Litestar 2.0.0b4):

{
	"request.scope['root_path']": "/api",
	"app.openapi_config.servers": [
		{
			"url": "/",
			"description": null,
			"variables": null
		}
	]
}

Proposed:

{
	"request.scope['root_path']": "/api",
	"app.openapi_config.servers": [
		{
			"url": "/api",
			"description": null,
			"variables": null
		}
	]
}

Drawbacks and Impact

No response

Unresolved questions

No response