refactored float packing on cpu/gpu

src/mol-canvas3d/canvas3d.ts

src/mol-geo/geometry/picking.ts

src/mol-gl/shader/chunks/assign-color-varying.glsl

src/mol-gl/shader/chunks/color-vert-params.glsl

src/mol-gl/shader/direct-volume.frag

src/mol-gl/shader/gaussian-density.frag

src/mol-gl/shader/utils/decode-float-log.glsl

src/mol-gl/shader/utils/decode-float-rgb.glsl

src/mol-gl/shader/utils/decode-id-rgb.glsl

src/mol-gl/shader/utils/encode-float-log.glsl

src/mol-gl/shader/utils/encode-float-rgb.glsl

src/mol-gl/shader/utils/encode-id-rgb.glsl

src/mol-math/geometry/gaussian-density/gpu.ts

src/mol-util/float-packing.ts