Upload sourcemaps to sentry.io

[saiichihashimoto]

Currently, sentry.io isn't receiving our sourcemaps.

Debugging the extension's errors is pretty impossible at this point.

• Uploads sourcemaps on release
• Sentry's issues show a proper stacktrace

https://docs.sentry.io/hosted/clients/javascript/sourcemaps/#using-sentry-cli

[saiichihashimoto]

The sourcemaps are now currently being uploaded, now we need to determine if sentry picks them up properly for issues. Chances are, we need to do something with the sourceMappingURL.

https://docs.sentry.io/hosted/clients/javascript/sourcemaps/#troubleshooting

[saiichihashimoto]

This isn't working for code within an eval statement, but that's acceptable as completing this issue.