fix typos in diffusion across semipermeable membranes

[#47659801]
layerPosition property is used to render images within a layer

This fixes the render order issues with image-layers and Diffusion Across a Permeable membrane by using layerPosition property from the classic MW models. The renderer uses this to order the svg image nodes accordingly such that the specified layer position order is respected by the rendering engine. The image-layers.mml -> image-layers.json conversion output test has the updated json output for the test to pass.
offset pore positions in diffusion across a semipermeable membrane interactive

[#47659801]
Fix call to trackEvent on model start

[#47831997]

this.trackEvent is undefined in this scope.
5f634dbb requires explicit widths for text wrapping

[#47836671]

Was that intended?
grapher: formatter() requires number not string

[#47833043]