[FEAT] UI/UX for stubs

[kallookoo]

Feature description or problem with existing feature
Currently the way to include the stubs is not friendly at all, since it is an array, creating that in the settings.json it spreads unnecessarily.

Describe the solution you'd like
I think there are two possibilities with rendered as editable lists:

1. Use the same option to include/exclude existing stubs of the type:

{
  "intelephense.stubs": {
    "apache": false,
    "wordpress": true,
    "woocommerce": "/home/user/dev/stubs/woocommerce.php" // The custom stub to include
  },
}

2. Create two options, intelephense.stubs and intelephense.stubsExcluded by example, each being of the type:

{
  "intelephense.stubs": [ "wordpress" ],
  "intelephense.stubsExcluded": [ "apache" ]
}

In both cases, for example in the README.md the available stubs are documented and that each user chooses.

Additional context
With this way of establishing stubs, we win in:

• Clearer use, both visually and in settings.json
• Possibility to include or overwrite stubs using the stubs path.