Re-order the names of the new pageColors options/preferences (PR 14874 follow-up)

Given that the new API-option is an Object named `pageColors`, with `background`/`foreground` keys, it occurred to me that it'd be slightly more consistent if the options/preferences names fully reflected that.

extensions/chromium/preferences_schema.json

@@ -209,12 +209,12 @@
       ],
       "default": -1
     },
-    "pageBackgroundColor": {
+    "pageColorsBackground": {
       "description": "The color is a string as defined in CSS. Its goal is to help improve readability in high contrast mode",
       "type": "string",
       "default": "Canvas"
     },
-    "pageForegroundColor": {
+    "pageColorsForeground": {
       "description": "The color is a string as defined in CSS. Its goal is to help improve readability in high contrast mode",
       "type": "string",
       "default": "CanvasText"

web/app.js

@@ -526,8 +526,8 @@ const PDFViewerApplication = {
       maxCanvasPixels: AppOptions.get("maxCanvasPixels"),
       enablePermissions: AppOptions.get("enablePermissions"),
       pageColors: {
-        background: AppOptions.get("pageBackgroundColor"),
-        foreground: AppOptions.get("pageForegroundColor"),
+        background: AppOptions.get("pageColorsBackground"),
+        foreground: AppOptions.get("pageColorsForeground"),
       },
     });
     pdfRenderingQueue.setViewer(this.pdfViewer);

web/app_options.js

@@ -129,12 +129,12 @@ const defaultOptions = {
     compatibility: compatibilityParams.maxCanvasPixels,
     kind: OptionKind.VIEWER,
   },
-  pageBackgroundColor: {
+  pageColorsBackground: {
     /** @type {string} */
     value: "Canvas",
     kind: OptionKind.VIEWER + OptionKind.PREFERENCE,
   },
-  pageForegroundColor: {
+  pageColorsForeground: {
     /** @type {string} */
     value: "CanvasText",
     kind: OptionKind.VIEWER + OptionKind.PREFERENCE,