✅(y-provider) add tests for y-provider server

We add jest tests for the y-provider server.
The CI will be able to run the tests.

src/frontend/servers/y-provider/jest.config.js

@@ -0,0 +1,11 @@
+var config = {
+  rootDir: './__tests__',
+  testEnvironment: 'node',
+  transform: {
+    '^.+\\.(ts)$': 'ts-jest',
+  },
+  moduleNameMapper: {
+    '^@/(.*)$': '<rootDir>/../src/$1',
+  },
+};
+export default config;