Fix objc colons getting incorrectly labels in fallback ternary case

[PoeticPete]

(Please review #4311 first. That will eliminate most of the changes in this stacked PR.)

Fixes #4310

The following gets formatted

    [[FOO alloc] target:true ? 1 : 2
                target2:ivar ?: fallback
                target3:ivar ?: fallback
                target4:1];

into

    [[FOO alloc] target:true ? 1 : 2
     target2 : ivar ?: fallback
     target3 : ivar ?: fallback
     target4 : 1];

cfg

sp_cond_colon                   = force
align_oc_msg_colon_span         = 1
indent_columns                  = 4
indent_with_tabs                = 0
indent_ternary_operator         = 2

This PR fixes it by early returning if there is a colon immediately after a question mark