publish(ci): Add "Prepare Release" GHA and Artifacts upload

[Lms24]

This PR prepares our CI for publishing our packages by

• adding the "Prepare Release" Github Action (analogously to sentry-javascript or sentry-bundler-plugins)
• uploading build artifacts to GH which craft pulls when publishing

Draft until #21 and #22 are merged

ref #15

[Lms24]

Tested upload - tarballs are all uploaded correctly: https://github.com/getsentry/rrweb/actions/runs/3990314259