Provide advanced roadmaps support for cross-project releases

Currently those fields aren't attached to a particular issue, and instead would require integration with the roadmaps API.

From the roadmap docs:

https://support.atlassian.com/jira-software-cloud/docs/create-a-cross-project-release-in-advanced-roadmaps/

Cross-project releases are only used in Advanced Roadmaps and cannot be saved to your issues in Jira.23A cross-project release is a way to align multiple single-project releases, 4and is only used for planning purposes in Advanced Roadmaps. They can’t be saved back to your Jira issues. 5When you save a cross-project release, only the single-project release associated with the teams in your plan 6will be updated.78To learn more about how cross-project releases are used in Advanced Roadmaps, 9see the How do single-project and cross-project releases differ? page.