add first version of chronos 3 rector

[LordSimal]

This is a first proposal for how chronos 3 rectors rules can look like. The main part this currently adjust is the Fewer mutation methods mentioned in https://github.com/cakephp/chronos/blob/2.next/docs/en/2-4-upgrade-guide.rst

I added 2 separate rules for chronos3-date and chronos3-datetime since they need to be handled separately. But maybe I don't see a way how this can easily be combined into one ruleset so help is very much appreciated 😄

Also can someone tell my why chained method calls like

$dateTime->addWeek()->subWeek();

only get changed to this?

$dateTime->addWeeks(1)->subWeek();

As you can see in the failed tests bellow only the first method call gets refactored but not the following (or any additional chained methods)

Is this a bug in rector or is there a special setting we need to add to also apply those changes to chained method calls?

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My main goal here is to get the base chronos class refactorings working so we only need to add our Cake\I18n\Date and Cake\I18n\DateTime classes to those respected rulesets.

[LordSimal]

I also don't really understand why we need a Makefile here...

[LordSimal]

maybe we should also make a separate 5.x branch for all the cake5 related rules...

[LordSimal]

I created a 5.x branch to justify the PHP8.1 requirement. But I will still try to remove the require-dev like mark story explained.

[LordSimal]

Anything else we can easily add for chronos related changes coming in Cake5?