Basic structure of the project

- Added a model with in-memory database, and routes, controller and
middleware to enable making initial CRUD calls to endpoints;

- Added jest and an initial test.

jest.config.ts

@@ -0,0 +1,11 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  moduleFileExtensions: ['ts', 'js'],
+  testMatch: ['**/tests/**/*.test.(ts|js)'],
+  globals: {
+    'ts-jest': {
+      tsconfig: 'tsconfig.json',
+    },
+  },
+};