Ensure that npm pack correctly packages workspaces with exposed executable

[stalgiag]

Addresses #3

This PR restructures this repo to accomplish the goals outlined in issue #3:

The bundle created by these commands should include the shared code as well as the relevant platform-specific code, and each should expose at-driver as an executable entry point with an identical command-line interface:

$ npm pack --workspace packages/macos-at-driver-server
$ npm pack --workspace packages/windows-at-driver-server

There were a few issues

• The bin location was defined in the wrong package.json
• Workspaces cannot reference files outside of the folder that holds the workspace's package.json for security reasons. As a previous workaround, I attempted to have a third private repo for the shared code. This causes npm to symlink the files in the workspace dependency to the parent workspace in node_modules. Unfortunately, these symlinked files are not included in any pack or publish output. As a further workaround, I am using the prepack step to copy the shared files into the workspaces and the postpack to remove any files copied this way.
• Lerna was included though it is not needed yet.

Remaining questions:

• The workaround for including the shared files in workspace output uses Unix commands. This prevents publishing on Windows. I can replace these with node scripts or another cross-platform solution if the overall direction is acceptable.

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1207383003324856

[jugglinmike]

This looks great, Stalgia! I really appreciate the simplicity and the care you're giving to the process. Let's go ahead with the cross-platform version.

[jugglinmike]

It's incredible what this removal does to the project's dependency tree.

[stalgiag]

I know! Lerna can do a whole lot. None of which are needed here yet.

[stalgiag]

Thanks! Added the node scripts to make the prepack and postpack cross-platform with this commit.

[jugglinmike]

The code looks good to me, and it works for both packages on both platforms. Nice going!