| Add `skhdr::Agtm` interface. | |
| Provide an interface to to create SMPTE ST 2094-50 (also known as Adaptive | |
| Global Tone Mapping) metadata. This interface includes parsing, serialization, | |
| and tone mapping (via an SkColorFilter). | |
| Add interface to set and get serialized AGTM metadata to `skhdr::Metadata`. | |