Add user-agent that created a release

[vladanpaunovic]

Sent the user-agent that created the release

• CLI
• Sentry Webpack Plugin
• Sentry Bundler Plugins
• Github Actions
• Vercel Integration

For JS projects, there are four primary ways of adding source maps to a release. Using the user-agent that created the release, we can detect how the release was created to give people specific instructions.

[scefali]

@vladanpaunovic got it already set up for the webpack plugin: getsentry/sentry-webpack-plugin#403 and it should already be set up for Github Actions and Vercel for a while