Do not force changing the assignee or reporter when keeping the issue in the same project during the move or bulk move operation or issue type migration

When changing an issue type scheme for a project some issues need to be moved to a new issue type.

Currently the assignee field checks if the assignee is assignable in the destination (project and issue type). During the issue type migration the project is the same.

At the moment, if a user was assignable and then lost these permissions, during the move operation the assignee would need to change. This could mean that a lot of issues need to be mdified.

We should consider to never force the assignee to change if the issue is staying in the same project.

At the moment, the reporter field checks for the create issue permission, and requires the reporter field to change if some of the existing reporters do not have this permission. Note, that when doing an issue type migration (changing an issue type scheme) the project stays the same.

We should consider to never force the reporter to change if the issue is staying in the same project or if the user doing the move has the Modify Reporter permission (in teh destination project).

If we do not decide to do the above, then at least present a list of issues and assignees and reporters that have to change during the move (or issue type migration).