Publish prebuilds for Linux (x64 and arm64)

[ItsHarper]

While the next version of this library should build fine on Linux, there won't be any Linux prebuilds included in the package, so the RHSPlib build will occur every time that the package is installed.

The way I envision this working is that there will be a GitHub Actions workflow that runs whenever a tag is published, which runs prebuildify --napi on a matrix of all supported platforms. All of the resulting prebuilds/<os>-<arch> folders will get combined into an artifact, and the prepublishOnly npm script will replace prebuildify --napi with a gh run download command to download the GitHub Actions artifact (https://cli.github.com/manual/gh_run_download) and extract it to the prebuilds folder.