Move getVisibleLayers to a new shared directory

This folder will include code shared by both the client-side app and the server!

The server isn't using it yet, but it will in a new API endpoint soon! I'm doing this in a separate commit to avoid lumping all the import-change noise into that commit.

src/app/WardrobePage/OutfitKnownGlitchesBadge.js

@@ -3,7 +3,7 @@ import { Box, VStack } from "@chakra-ui/react";
 import { WarningTwoIcon } from "@chakra-ui/icons";
 import { FaBug } from "react-icons/fa";
 import { GlitchBadgeLayout, layerUsesHTML5 } from "../components/HTML5Badge";
-import getVisibleLayers from "../components/getVisibleLayers";
+import getVisibleLayers from "../../shared/getVisibleLayers";
 
 function OutfitKnownGlitchesBadge({ appearance }) {
   const glitchMessages = [];

src/app/WardrobePage/PosePicker.js

@@ -19,7 +19,7 @@ import {
 import { loadable } from "../util";
 
 import { petAppearanceFragment } from "../components/useOutfitAppearance";
-import getVisibleLayers from "../components/getVisibleLayers";
+import getVisibleLayers from "../../shared/getVisibleLayers";
 import { OutfitLayers } from "../components/OutfitPreview";
 import SupportOnly from "./support/SupportOnly";
 import useSupport from "./support/useSupport";

src/app/components/OutfitThumbnail.js

@@ -5,7 +5,7 @@ import gql from "graphql-tag";
 import getVisibleLayers, {
   petAppearanceFragmentForGetVisibleLayers,
   itemAppearanceFragmentForGetVisibleLayers,
-} from "./getVisibleLayers";
+} from "../../shared/getVisibleLayers";
 
 function OutfitThumbnail({ petAppearance, itemAppearances, ...props }) {
   return (

src/app/components/useOutfitAppearance.js

@@ -4,7 +4,7 @@ import { useQuery } from "@apollo/client";
 import getVisibleLayers, {
   itemAppearanceFragmentForGetVisibleLayers,
   petAppearanceFragmentForGetVisibleLayers,
-} from "./getVisibleLayers";
+} from "../../shared/getVisibleLayers";
 
 /**
  * useOutfitAppearance downloads the outfit's appearance data, and returns