Adds change command to create a change request

Creates a new command:

/woodhouse change declare

This introduces some small workflow changes for change management:

• Moving the date to “Due Date” on the issue
• Adding a mandatory reviewer which is selected from a member of gl-infra/
• Adding a mandatory list of service(s) which is picked from the service labels

You can try it out in #woodhouse-staging

Dependencies

• There was as small refactor to share code between incident and change creation, I put this refactor in a separate MR to make it easier to review !102 (merged)
• We need to update the change template production!71 (merged)

For https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/13330