Warn on unused disables

[andy-hanson]

When there is a // tslint:disable-line foo-rule comment, we should verify that foo-rule has a failure on that line. Similar for disable-next-line.
For // tslint:disable we should verify that at least one rule has a failure in the disabled range.

Depends on #2369, since if we're doing this, we can't allow rules to do anything "smart" with the disable intervals.

[adidahiya]

dupe of #1330