Fix all tests on Windows and add run-script for Walkontable watch (#5878)

[warpech]

Context

Continuation of #6128. This fixes #5878

I need this change, because I am using a Windows desktop PC for development. That's because time npm run build takes 53s on Windows and 1m21s on macOS.

How has this been tested?

Run the following scripts on Windows with success:

npm run test
npm run test:walkontable
npm run test:walkontable.watch
npm run test:e2e
npm run test:e2e.watch
npm run test:unit
npm run test:unit.watch

As well as manually running spec runners in Chrome:

• http://localhost:5000/test/E2ERunner.html
• http://localhost:5000/src/3rdparty/walkontable/test/SpecRunner.html

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature or improvement (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Additional language file or change to the existing one (translations)

Related issue(s):

1. npm task for unit tests throws errors on Windows. #5878

Checklist:

• My code follows the code style of this project,
• My change requires a change to the documentation.

[mrpiotr-dev]

Seems to work OK.
Although, sometimes npm run test:walkontable.watch doesn't run tests until you make change in the code (on macOS).
On Window, killing a watch task works strange:

And then you need to use CTRL+C many times or reopen Command prompt window.

[warpech]

I have addressed all comments, except of this one:

Although, sometimes npm run test:walkontable.watch doesn't run tests until you make change in the code (on macOS).

I have noticed it too, but I don't know what to do about it :(

[mrpiotr-dev]

LGTM 👍