Add missing <optional> include to drm.h

[oadlebai]

DrmRenderer::DrmProperty uses std::optional but drm.h never includes <optional>, relying on it being pulled in transitively by another header. That isn't guaranteed and fails to compile with GCC 13 / libstdc++ on aarch64:

drm.h:89:14: error: 'optional' in namespace 'std' does not name a template type
   89 |         std::optional<std::pair<uint64_t, uint64_t>> range() const {
drm.h:16:1: note: 'std::optional' is defined in header '<optional>'; did you forget to '#include <optional>'?

The sibling header eglimagefactory.h already includes <optional> explicitly for the same reason. This adds the include to drm.h alongside the other standard-library headers.