[CodeCompletion] Don't report an extra argument failure if the code completion token is the first one in a call
[CodeCompletion] Don't report an extra argument failure if the code completion token is the first one in a call

This makes sure we don't penalize overloads with no arguments when calling
```swift
func foo() {}
func foo(_ arg: Int) {}
foo(#^COMPLETE^#
```

ahoppen/swift,ahoppen/swift,roambotics/swift,glessard/swift,apple/swift,ahoppen/swift,benlangmuir/swift,ahoppen/swift,apple/swift,atrick/swift,JGiola/swift,benlangmuir/swift,benlangmuir/swift,gregomni/swift,roambotics/swift,apple/swift,benlangmuir/swift,apple/swift,apple/swift,JGiola/swift,roambotics/swift,gregomni/swift,atrick/swift,gregomni/swift,JGiola/swift,glessard/swift,apple/swift,glessard/swift,benlangmuir/swift,roambotics/swift,glessard/swift,JGiola/swift,JGiola/swift,JGiola/swift,gregomni/swift,atrick/swift,glessard/swift,glessard/swift,benlangmuir/swift,atrick/swift,roambotics/swift,atrick/swift,gregomni/swift,atrick/swift,ahoppen/swift,gregomni/swift,ahoppen/swift,roambotics/swift