Fix minor packaging issues in automation lib

[jasongin]

This PR fixes some minor issues that affected building and consumption of the automation library externally via an npm package:

• Remove the postinstall npm script. This should not be run after installing the automation package because the npm package includes only the already-compiled output. And that script is not necessary for vscode smoketests because the smoke package runs yarn --cwd ../automation compile during its compilation.
• Fix the driver module export in index.ts.
• Add .npmignore
• Update .gitignore

None of these changes should have any impact on building or running the vscode smoke tests. Anyway, I verified that the vscode smoke tests are still passing.

[jasongin]

@Tyriar

[Tyriar]

Works fine here 👍

[Tyriar]

Hmm, using && didn't used to work on Windows but it seems fine now in both Pipelines and Actions, guess that's fine.

[jasongin]

Thanks!