updated the jest configuration to generate a coverage report on the entire project when tests are run. this coverage report has been added to the the gitignore file as it is not relevant to store it in the online repository.
ref: N25B-114
also added an example test for the counter in the components.tsx file to demonstrate functionality of testing configuration. installed all dependencies for testing using --save-dev to make sure they are stored as dev dependencies
ref: N25B-212
