Properly add "families" if there is >1 entry.
Properly add "families" if there is >1 entry.

The only uses that didn't set mandatory were ios_static_framework and
_ios_test_bundle. _ios_test_bundle is an impl detail without the two
test rules, but neither seems to document the `families` attribute.

Fixes #149

PiperOrigin-RevId: 187912334

bazelbuild/rules_apple,bazelbuild/rules_apple,bazelbuild/rules_apple,bazelbuild/rules_apple