Implement a release script

[brobeson]

Extension Version

v0.1.0

What's the feature?

The release process should:

• Ensure all references to the version in the code are up to date.
• Build the vsix.
• Create a GitHub release.
• Upload the vsix to the GH release.
• Tag the repository.
• Publish the extension to the marketplace.

Offload as much as possible to a GH workflow.