Implement read support for CDN3

ts/textsecure/WebAPI.ts

@@ -1203,6 +1203,9 @@ export function initialize({
   if (!isString(cdnUrlObject['2'])) {
     throw new Error('WebAPI.initialize: Missing CDN 2 configuration');
   }
+  if (!isString(cdnUrlObject['3'])) {
+    throw new Error('WebAPI.initialize: Missing CDN 3 configuration');
+  }
   if (!isString(certificateAuthority)) {
     throw new Error('WebAPI.initialize: Invalid certificateAuthority');
   }
@@ -2655,7 +2658,7 @@ export function initialize({
       const abortController = new AbortController();
 
       const cdnUrl = isNumber(cdnNumber)
-        ? cdnUrlObject[cdnNumber] || cdnUrlObject['0']
+        ? cdnUrlObject[cdnNumber] ?? cdnUrlObject['0']
         : cdnUrlObject['0'];
       // This is going to the CDN, not the service, so we use _outerAjax
       const stream = await _outerAjax(`${cdnUrl}/attachments/${cdnKey}`, {

ts/types/RendererConfig.ts

@@ -33,6 +33,7 @@ export const rendererConfigSchema = z.object({
   buildExpiration: z.number(),
   cdnUrl0: configRequiredStringSchema,
   cdnUrl2: configRequiredStringSchema,
+  cdnUrl3: configRequiredStringSchema,
   challengeUrl: configRequiredStringSchema,
   certificateAuthority: configRequiredStringSchema,
   contentProxyUrl: configRequiredStringSchema,

ts/windows/main/phase2-dependencies.ts

@@ -31,6 +31,7 @@ window.WebAPI = window.textsecure.WebAPI.initialize({
   cdnUrlObject: {
     0: config.cdnUrl0,
     2: config.cdnUrl2,
+    3: config.cdnUrl3,
   },
   certificateAuthority: config.certificateAuthority,
   contentProxyUrl: config.contentProxyUrl,