TASK: Yield events to publish in workspace command handler

[mhsdesign]

1.) Allow command handlers to yield EventsToPublish

Using generators will allow us to omit the direct publishing via ->publishEvents or sub command handling via ->handle

For exception cases - on a ConcurrencyException - it will be possible to notice the failure in the command handler and act accordingly (by emitting another event and than raising another error).
If try catch is used the ConcurrencyException will be rethrown into the outer world:

try {
   yield EventsToPublish();
} catch (ConcurrencyException $e) {
   yield $restoreState();
   throw $e;
}

Catchups will be invoked after each yield to ensure that the system is atomic.

2.) Cleanup RebasableToOtherWorkspaceInterface extraction
And enforce type of RebasableToOtherWorkspaceInterface earlier.

To be noted: The rebase and discard operation previously only required fromArray to be implemented, now we also strict check against: RebasableToOtherWorkspaceInterface

3.) Avoid use of sub commands in WorkspaceCommandHandler
rebase, discard & publish individual will be migrated via #5301

Upgrade instructions

Review instructions

Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[bwaidelich]

This looks great already! Some first comments

[mhsdesign]

fyi as we do a rebase now instead of failing if a rebase is necessary, we dont need the error handling:

    try {
        yield $publishContentStream;
    } catch (ConcurrencyException $exception) {
        yield $this->reopenContentStream(
            $workspace->currentContentStreamId,
            $currentWorkspaceContentStreamState,
            $commandHandlingDependencies
        );

        throw new BaseWorkspaceHasBeenModifiedInTheMeantime(sprintf(
            'The base workspace has been modified in the meantime; please rebase.'
            . ' Expected version %d of source content stream %s',
            $publishContentStream->expectedVersion->value,
            $baseWorkspace->currentContentStreamId
        ));
    }

and thus i removed the complexity -> 3679157