Display migrations inconsistency on issues

[DifferentialOrange]

trafficstars

In case migrations are not the same on instances (for example, it had failed on one of them), I see a warning on Migrations tab, but it would be nice to see in in cluster issues as well.

Everything is bad:

But everything if ok on the main page:

[yngvar-antonsson]

I propose to add an issue to a migrator role.

References: https://github.com/tarantool/cartridge/blob/7eb0ad9f79bee5bc5a0f4b527fc5c456029c27f7/test/integration/issues_test.lua#L494

https://github.com/tarantool/cartridge/blob/7eb0ad9f79bee5bc5a0f4b527fc5c456029c27f7/cartridge/user-defined-role.lua#L49