Remove non-deprecated extension packages from this repository

[AdmiringWorm]

We currently are hosting extension packages in this repository, a new repository to host extension packages have been created and these extension packages should be moved over to that repository instead.

The packages that need to be removed from this repository is:

• Remove chocolatey-azuredata.extension package
• Remove chocolatey-core.extension package
• Remove chocolatey-vscode.extension package

Additionally, there are some packages located in this repository, so there is a need to install these extensions using Chocolatey CLI on appveyor and make sure that the packages using these packages are updated to not reference local packages anymore.

This issue is heavily dependent on the issue in the new repository: chocolatey-community/chocolatey-extensions#5