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Umbrella bug #130921.

Blocked on: #130924

DeviceBuffers are Impeller's shared buffer abstraction and are used for transferring data from the CPU memory to GPU memory. For example, this is how uniform buffers are written and accessed.

Implement dart.gpu.DeviceBuffer.copyByteBuffer(), which allows for populating a DeviceBuffer by supplying a ByteBuffer and a range in Dart. Perform reasonable OOB checks and expose useful errors.