Set Up Vitest for RealmsWorld

[4eyes52]

Creates vitest.config.ts in root of apps/nextjs

Adds example __tests__ directory to src/utils that includes a mock for tokenDetails and tests for getTokenName utility function. The idea being that if test coverage is needed for code in specific directories within the nextjs app, new __tests__ directories can be added to the directory where test coverage is needed instead of having one giant __tests__ directory at the root of the nextjs app for all tests. I think its cleaner and easier to manage test files this way but to each their own.

Adds new commands to package.json scripts in the nextjs app. "test": "vitest" & "testUI: "vitest --ui"

running pnpm run test inside the root of apps/nextjs directory will run all tests that exist inside the nextjs app. Depending on your needs, it may be easier to read coverage reports in the terminal by running this command inside the specific directory you are currently working in for smaller coverage reports.

running pnpm run testUI will open vitest's UI interface automatically and the interface updates automatically as changes are saved to test files. I tend to use the UI interface when I want to get a better idea of what lines are missing coverage for the code that Im adding tests for.

React Testing Library is also added as a package here for testing components.