fix(shader_ui_controls): exclude empty shaderControls property from JSON state
fix(shader_ui_controls): exclude empty shaderControls property from JSON state

google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,janelia-flyem/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer