Add a separate tsconfig for excluding tests/mocks from builds, while leaving them for type checks

tsconfig.build.json

@@ -0,0 +1,15 @@
+// For builds, excludes tests and mocks
+{
+  "compilerOptions": {
+    "target": "es2016",
+    "module": "commonjs",
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "outDir": "dist",
+    "sourceMap": true
+  },
+  "include": ["src"],
+  "exclude": ["**/__tests__/*/**", "**/__mocks__/*/**"]
+}