Order update events

[Zales0123]

In this PR I added two events that can be thrown when the order is updated:

• OrderUpated that is always thrown
• PaidOrderTotalChanged that is thrown if the order was already paid - it can be useful to subscribe for for refund or gift cards functionality

• another bunch of refactoring

[codecov]

Codecov Report

Attention: Patch coverage is 71.87500% with 9 lines in your changes missing coverage. Please review.

Project coverage is 70.54%. Comparing base (62a38d4) to head (e4fbb72).

Files	Patch %	Lines
...ndencyInjection/SetonoSyliusOrderEditExtension.php	0.00%	7 Missing ⚠️
src/Entity/EditableOrderTrait.php	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master       #8      +/-   ##
============================================
- Coverage     71.42%   70.54%   -0.89%     
- Complexity       52       58       +6     
============================================
  Files            23       26       +3     
  Lines           273      292      +19     
============================================
+ Hits            195      206      +11     
- Misses           78       86       +8     

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