[api-minor] Use a local font or fallback on an embedded one (if it exists) for non-embedded fonts (bug 1766039)

- Replace FoxitSans with LiberationSans: LiberationSans is already there (for XFA) and we can use
it as a good replacement of FoxitSans.
- For now we just try to substitue standard fonts, the strategy is the following:
  * we try to find a font locally from a hardcoded list;
  * if it fails then we use Liberation as fallback (only for Helvetica for the moment);
  * else we just fallback on the system serif/sansserif/monospace font.

web/app_options.js

@@ -210,7 +210,12 @@ const defaultOptions = {
   cMapUrl: {
     /** @type {string} */
     value:
-      typeof PDFJSDev === "undefined" ? "../external/bcmaps/" : "../web/cmaps/",
+      // eslint-disable-next-line no-nested-ternary
+      typeof PDFJSDev === "undefined"
+        ? "../external/bcmaps/"
+        : PDFJSDev.test("MOZCENTRAL")
+        ? "resource://pdf.js/web/cmaps/"
+        : "../web/cmaps/",
     kind: OptionKind.API,
   },
   disableAutoFetch: {
@@ -271,8 +276,11 @@ const defaultOptions = {
   standardFontDataUrl: {
     /** @type {string} */
     value:
+      // eslint-disable-next-line no-nested-ternary
       typeof PDFJSDev === "undefined"
         ? "../external/standard_fonts/"
+        : PDFJSDev.test("MOZCENTRAL")
+        ? "resource://pdf.js/web/standard_fonts/"
         : "../web/standard_fonts/",
     kind: OptionKind.API,
   },