Add working Jest & TypeScript config

- Jest now uses ts-jest for transforms
- TypeScript compilation via `lerna run tsc`

jest.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  clearMocks: true,
+  moduleFileExtensions: ['js', 'ts'],
+  roots: ['<rootDir>/packages'],
+  testEnvironment: 'node',
+  testMatch: ['**/__tests__/*.test.ts'],
+  testRunner: 'jest-circus/runner',
+  transform: {
+    '^.+\\.ts$': 'ts-jest'
+  },
+  verbose: true
+}