[Issue Stream] Add runtime context to group details

In PR https://github.com/getsentry/sentry/pull/88312, runtime labels for JS Errors were added. Those "Frontend" and "Backend" labels should also be added to issue stream items like this (only JS SDK issues):  In the event details, this runtime context information is retrieved from the already existing event details. In the issue stream, this runtime information is not available, as the backend returns grouped issues. Develop Docs: [Runtime Context](https://develop.sentry.dev/sdk/data-model/event-payloads/contexts/#runtime-context) Including the runtime context issue stream probably requires the following changes: - Changing the `issues` endpoint: `OrganizationGroupIndexEndpoint` - Including `runtime` to the data here (is returned in the `issues` endpoint): https://github.com/getsentry/sentry/blob/af33c2a5cc89a7cb5b5fb9307ee40cbddc5677c2/src/sentry/models/group.py#L598-L600 - Getting the runtime on Relay and adding it to the data dict mentioned above. related to https://github.com/getsentry/sentry/issues/85732