feat: Introduce jest for backend tests

packages/backend/package.json

@@ -10,7 +10,7 @@
     "build:watch": "nodemon --watch 'src/**/*.ts' --watch 'bin/**/*.ts' --exec yarn build --ext ts",
     "start": "node dist/src/server.js",
     "pretest": "APP_ENV=test ts-node ./test/setup/prepare-test-env.ts",
-    "test": "APP_ENV=test ava",
+    "test": "APP_ENV=test jest",
     "lint": "eslint . --ignore-path ../../.eslintignore",
     "db:create": "ts-node ./bin/database/create.ts",
     "db:seed:user": "ts-node ./bin/database/seed-user.ts",
@@ -121,6 +121,7 @@
     "@types/crypto-js": "^4.0.2",
     "@types/express": "^4.17.15",
     "@types/http-errors": "^1.8.1",
+    "@types/jest": "^29.5.5",
     "@types/jsonwebtoken": "^8.5.8",
     "@types/lodash.get": "^4.4.6",
     "@types/memory-cache": "^0.2.2",
@@ -132,8 +133,10 @@
     "@types/pino": "^7.0.5",
     "@types/pluralize": "^0.0.30",
     "@types/showdown": "^2.0.1",
+    "jest": "^29.7.0",
     "nodemon": "^2.0.13",
     "sinon": "^11.1.2",
+    "ts-jest": "^29.1.1",
     "ts-node": "^10.2.1",
     "ts-node-dev": "^1.1.8"
   },