Normalize package.json files, to prepare publication on NPM

[Kocal]

Q	A
Bug fix?	no
New feature?	no
Issues	Fix #...
License	MIT

This is a first iteration for #2575: rework our package.json files in order to make them more "friendly" and work on npm.

Next steps:

1. Add some verifications, to ensure PHP and JS versions of a same package are identical (and so 100% compatible)
2. See how we can deploy JS packages when creating a new UX releases. I'm thinking about a full automated process using the CI with a workflow listening on tag creation, which will be responsible to upgrade the version from package.json files, commit, push, and publish to npm)
3. Check if we need to manually create the packages on npm before trying to publishing them

[smnandre]

Ho yes one thing. Would the LICENCE be published with these settings? Or do we need to duplicate the repository one in the assets directory ?

[Kocal]

We already have "license": "MIT" defined in package.json files, but it's true that's make sense to ship the LICENSE file in javascript packages.

I'm on it

EDIT: it means that we also need a README.md file for each packages aswell

[Kocal]

Files README.md and LICENSE added!

[Kocal]

@symfony/ux-map will need a special treatment, since bridges dist files already include the dist/abstract_map_controller.js from @symfony/ux-map, it means that there is no need to publish it as a npm package.

For the same reasons, installing symfony/ux-map with composer should not update the package.json, which is the case today:

        "@symfony/ux-leaflet-map": "file:vendor/symfony/ux-leaflet-map/assets",
        "@symfony/ux-map": "file:vendor/symfony/ux-map/assets",

EDIT: see #2611

[Kocal]

Added "private": true to src/Map/assets/package.json, this way we can easily exclude Map package from yarn workspaces ... commands with the help of --no-private.

Next steps:

1. Check PHP / JS packages versions sync
2. Ensure all packages can be installed correctly from npm (@symfony/ux-leaflet-map works fine) manually and automatically with a CI workflow
3. Deploy the packages on npm
4. Ensure all pacakges can be installed correctly from jsdelivr
5. Write a CI workflow to automatically bump versions (of all packages) and publish packages (except private ones)