Refactor entire project (#39)

- Use more modern TypeScript conventions
- Use JavaScript Kubernetes Client
- Add unit tests
- Add integration tests
- Add TypeScript compile verify workflow
- Switch codeowners

tests/util.ts

@@ -0,0 +1,7 @@
+/**
+ * Returns error thrown by core.getInput when input required but not found
+ * @param inputName Name of input
+ * @returns Error with explanation message
+ */
+export const getRequiredInputError = (inputName) =>
+  Error(`Input required and not supplied: ${inputName}`);