feat: Rework how we track sessions

[HazAT]

How we track session now:

• We create a session on page load
• We send the session with init: true and status: ok -> After sending the session switches to init: false in the scope
• If there is a handled error, we increment error: +1 and send the update
• If there is an unhandled error, we increment error: +1, set status: crashed and send the update
• On navigation changes, we end the previous session
  -- If the Session was status: crashed it stays status: crashed
  -- If the Session was status: ok it will be changed to status: exited

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	20.23 KB (-0.55% 🔽)
@sentry/browser - Webpack	21.14 KB (-0.4% 🔽)
@sentry/react - Webpack	21.16 KB (-0.41% 🔽)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	27.26 KB (-0.08% 🔽)

[lobsterkatie]

Just some naming questions (you know me!). Also, do we have any tests covering this?

Otherwise, looks good. 🙂

[HazAT]

I will prepare a beta release from this branch so we can test it on sentry.io

[lobsterkatie]

👍🏻

[HazAT]

sentry.io PR
getsentry/sentry#23538