Currently the version checker makes it a CI error to change the major version of a plugin's platform interface. This isn't the right behavior, since we don't forbid them, we just want to be careful about doing them only when necessary, and in the least disruptive way possible. We shouldn't just remove the check though, since it's a good way to prevent someone from writing or approving a change without going through enough consideration because they didn't notice.

We'll need to add a way to annotate the change to override the error check (e.g., a comment on the version line in the pubspec). We should also make sure that the checks verify that any other version bump does not have that marker, so that its removal in enforced rather than it just being accidentally left indefinitely, turning off all future checking of that plugin.