4.0.0-beta.1

Updating the underlying Sentry JavaScript SDK's to v7 forces a major version bump due to minor breaking changes in user
facing APIs. Be sure to check out the migration doc.

Upgrading to v7 of the Sentry JavaScript SDKs (#471):

• Minor internal changes due to API changes and deprecations
• Rewrite transports to use new functional API
• Simplify minidump submission since the underlying SDKs now support attachments

Other additions and fixes:

• feat: Add ability to explicitly control offline mode (#489)
• feat: Allow closing of SDK (#467)
• feat: Optionally attach screenshots (#510)
  • Disabled by default - Screenshots may contain PII
• fix: Ensure environment is overridden for minidumps (#497)
• fix: Pass correct event to beforeSend (#481)
• fix: Correctly parse mixed Chrome/node stack traces in the renderer (#509)