Pull request builder should give preview of types-publisher results

[efokschaner]

@andy-ms @RyanCavanaugh
I recently submitted a PR that had some unexpected results when run through the types-publisher. See this follow-up PR for context and an attempted fix.

This made me realise it would be nice to get more feedback from the types-publisher step as part of the pull request build. Maybe something as far-fetched as having the PRB generate a real pre-release package on npm so that end-to-end testing with the PR's npm package can be done?

[ghost]

I don't think this will be necessary if we properly ban a .d.ts from appearing in a test folder (microsoft/types-publisher#339). Then the publish will just be the files you wrote plus a package.json and README.md generated automatically.

[efokschaner]

Thanks @andy-ms, that would definitely help in the specific situation i was in. Feel free to close this issue if there's nothing else we want to do on this matter.