Split before interface name in RequireClause only if the interface has internal splits

Split before interface name in RequireClause only if the interface has internal splits

Summary:
It looks inconsistent when we break before a long interface name in a list of `RequireClause`s:

```
require implements ShortNameWithNoSplits;
require implements
  LongNameWithNoSplits________________________________________;
require implements AnotherShortName;
require implements AFinalShortName;
```

After this change we avoid breaking between `require implements` and the interface name when the interface contains no splits (e.g., around generic parameters). This makes lists of `require implements` clauses (without internal splits) look more consistent.

Reviewed By: pittsw

Differential Revision: D7477201

fbshipit-source-id: b0c5c9acb136ce666b820e3118a95c51f16219a7