fix(auth-server): Restore fxa-shared/* jest moduleNameMapper

Because:
- When jest.config.js switched to pathsToModuleNameMapper, the explicit
  '^fxa-shared/(.*)$' → '<rootDir>/../fxa-shared/$1' mapping was dropped.
  Without it, 'require("fxa-shared/...")' resolves through fxa-shared's
  "exports" field in node_modules, which points at un-built dist/ paths,
  breaking integration tests like oauth_api.in.spec.ts's POST
  /authorized-clients (response schema validation path was never reached
  — the underlying fxa-shared sub-path import failed at module load).

This commit:
- Adds back the fxa-shared subpath mapping alongside the tsconfig path
  mappings so both schemes coexist during jest runs.

Author: dschom

packages/fxa-auth-server/jest.config.js

@@ -25,6 +25,7 @@ module.exports = {
     ...pathsToModuleNameMapper(compilerOptions.paths, {
       prefix: '<rootDir>/../../',
     }),
+    '^fxa-shared/(.*)$': '<rootDir>/../fxa-shared/$1',
   },
   testTimeout: 10000,
   maxWorkers: 4,