feat: Update to v8.51.0 of the JavaScript SDKs

[timfish]

Recent changes in @sentry/core means it now handles setting the sessions as crashed for us when level: 'fatal', so we no longer have to set the sessions crashed manually. This means that beforeSend now behaves the same for both native and JavaScript events and skips marking the session as crashed if beforeSend returns null.

• Closes Native events ignored via beforeSend still impact release health #1062

The only slight complication is minidumps found at startup. In this case:

• We restore the previous session to the current scope
• Let events be reported and crash the previous session
• Restore the session for this app run to the current scope

Because core is now handling sessions, we get fewer ok session updates sent but these do not impact overall session states.