Fix snapshot setting when create/update operation made

[Jurigag]

Hello!

• Type: bug fix
• Link to issue: Phalcon 2.0.* - creating object does not set model snapshots. #11007, [NFR] Implement Model snapshot loading call #11818, Dynamic updates / snapshot data work correctly only once #11424

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• I have read and understood the Contributing Guidelines?
• I have checked that another pull request for this purpose does not exist.
• I wrote some tests for this PR.

Small description of change: This is adding setting snapshot to correct one when creating/updating model operation were succesfully made.

Thanks

[Jurigag]

Old tests were written in wrong way, for bugged feature, making this change breaking them(getChangedFields were made in wrong place). I will fix them in this PR too.

[sergeyklay]

Thank you