[licenses] productify license check for plugins (builtins + external extensions)

[vince-fugnitto]

Description

In order to verify the license checks for the builtin extensions, some extra steps were required to do so since such plugins are not hoisted to the repository's node_modules. The steps were to walk through the available extensions under vscode/extensions in order to obtain the list of package.json and collect their dependencies. These dependencies were then added to a package.json which was built, and generated a package.lock.json which was used in Clearly Defined. The goal is to eventually automate this process better and productify it so we can re-use it in the future if need be.

The current steps:

1. clone the vscode repository
2. build the repo (yarn)
3. cd extensions
4. install the package-deps tool
   used to iterate over the available package.json under a directory and collect the dependencies
5. run the command package-deps -d **package.json > dependencies.txt
6. in a new folder, run the command npm init -y
7. add the dependencies from dependencies.txt to the new package.json
8. perform npm i (installs dependencies and generates a package.lock.json)
9. copy the package.lock.json to clearly defined and verify for any invalid licenses