This matches the same API usage as attributes/ops/types. For example:
```c++
Dialect *dialect = ...;
// Instead of this:
if (auto *interface = dialect->getRegisteredInterface<DialectInlinerInterface>())
// You can do this:
if (auto *interface = dyn_cast<DialectInlinerInterface>(dialect))
```
Differential Revision: https://reviews.llvm.org/D117859
58e7bf78a3