Add development playground

[genu]

Is your feature request related to a problem? Please describe.

When contributing, It would be great if there was a playground built in to easily get a development environment setup and start working.

Currently there's only a way to build and run tests/coverage

I'd like an easier way to contribute, or a documented way to get things up and running fast.

Describe the solution you'd like

I'd like to be able to clone the repo, run something like pnpm dev and be able to start testing changes in the vee-validate package.

Describe alternatives you've considered

Having made contributions, I had to create my own playground, install the package from npm, modify the built package in node_modules and then copy my changes back into the src of vee-validate