[Replay] Upstream replay event sending

[mydea]

Currently, replay events are sent from the replay package in a somewhat "custom" way, buy accessing a bunch of private methods on the hub etc.

We should refactor this so that the replay event types are part of the general API, and so that the replay package can use public APIs for everything.

• ref(replay): Avoid using private hub._withClient #6494
• fix(replay): Replace _waitForError with recordingMode #6489
• feat(core): Add scope.getLastBreadcrumb() #6495
• feat(core): Expose prepareEvent util function #6517
• ref(replay): Stop calling _updateSessionFromEvent #6510

[Lms24]

Once this is implemented, I think we can revert a good part of #6493 (probably not _breadcrumbs though)

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀