Add new "after" pagination option to resource api's

[glinton]

For more information on the after option, see #19218

Pagination options implementation should be unified as well. Tasks handles pagination options differently than other resources, like dashboards. Checks seem to follow the pattern of tasks, but don't implement pagination options at all.

From a consumer perspective, not much would change. According to the swagger, tasks' limit is 500, where everything else is 100.