refactor: migrate spinner to use import/export

[ghost]

Considering NodeJS more or less supports ES modules now natively, I was checking to see how close we are to building CLI using ES modules. The only thing stopping us TypeScript-wise seems to be the spinner module. So I've migrated that. The only thing left after this is the various JS modules.

Notes

There's some odd logic around isRequired. I think this was for tests and import flows which we no longer provide. So it's no longer needed. See: #2371

The isCI check is also kind of weird. It looks like we can check the environment if it's TTY instead to decide whether or not to render the spinner. Kind of like how we render colours.

I don't want to get too deep into improving spinner's code/types as we may want to replace it with a library. Especially if we want to show better progress updates (e.g. percentages, fractions, etc.).

[github-actions]

	Warnings
⚠️	Since the CLI is unifying on a standard and improved tooling, we're starting to migrate old-style imports and exports to ES6 ones. A file you've modified is using either module.exports or require(). If you can, please update them to ES6 import syntax and export syntax. Files found: src/cli/commands/monitor/index.ts src/cli/commands/protect/wizard.ts src/lib/plugins/nodejs-plugin/npm-modules-parser.ts src/lib/snyk-test/run-test.ts src/lib/spinner.ts
⚠️	You've modified files in src/ directory, but haven't updated anything in test folder. Is there something that could be tested?

	Messages
📖	This PR will not trigger a new version. It doesn't include any commit message with feat or fix.

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[maxjeffos]

Made a couple suggestions but approved it.