expiring-todo-comments - more specific error message for missing conditions

[mmkal]

Rather than falling back to no-warning-comments when "useless" todos are found, could the rule explicitly report something like TODO comment should have a condition or due date?

When I first saw Unexpected "todo" comment I thought "oh, this is a rule which aggressively says 'todos are bad'", and I turned it off. Later, I spent a bunch of time implementing a worse version of expiring-todo-comments, which parsed ISO dates. Eventually I stumbled across the docs and realised how useful this rule really is.

Basically the problem is that it's piggy-backing off eslint's error message, which is too broad and doesn't really nudge the user into fixing the problem - and risks pushing them into deleting the todo or turning off the rule.