refactor event appeared callbacks

[prolic]

@pkruithof note this change as well

[coveralls]

Pull Request Test Coverage Report for Build 334

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 13 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.2%) to 67.099%

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Files with Coverage Reduction	New Missed Lines	%
src/Exception/PersistentSubscriptionCommandFailedException.php	6	0.0%
src/PersistentSubscriptions/PersistentSubscriptionsClient.php	7	72.04%

Totals
Change from base Build 333:	-0.2%
Covered Lines:	4289
Relevant Lines:	6392

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💛 - Coveralls

[prolic]

Also resolves #44

[pkruithof]

As it seems, only internal stuff has changed, right? There were some points where we had to require internal classes, so I'll check those. But this mostly shouldn't affect anything, I think.

[prolic]

Mostly internal stuff, correct. But note your callbacks expect ResolvedEvent now and not Internal\ResolvedEvent.

[pkruithof]

Yeah, already updated those :-)

The only internal class I need to use right now is Prooph\EventStoreClient\Internal\EventStorePersistentSubscription