feat(python): add SingleMeshLayer viewer state wrapper
feat(python): add SingleMeshLayer viewer state wrapper

seung-lab/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,seung-lab/neuroglancer,seung-lab/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,google/neuroglancer,google/neuroglancer,google/neuroglancer,seung-lab/neuroglancer,janelia-flyem/neuroglancer