Change behavior to skip reconfirmation after creating a record with #save called in callback

[ArneZsng]

The following commit was breaking stuff on our system for a new email confirmation when the email is changed while the object is still in memory:
1d57169

This is due to skip_reconfirmation! in send_on_create_confirmation_instructions because it sets @bypass_confirmation_postpone to true which lets postpone_email_change? return false.

The case was added to the confirmable test case. Basically, the skipping of the reconfirmation as part of an after_create hook needs to be treated differently from a general bypass. To ensure that this is skipped when save is called in an after_create hook but NOT if the email is changed from an existing email, additional checks were added.

[ulissesalmeida]

A little typo here reconfirmation

[ulissesalmeida]

Looks good to me. Any consideration @josevalim @lucasmazza

I think it may need a backport to 3.5.x.

[lucasmazza]

@ArneZsng @ulissesalmeida I feel like we should have better names to express the checks for dealing with the save + after_create scenarios - skip_create_confirmation sounds like we are skipping the confirmation on a regular create scenario, regardless of the callback issue.

[ArneZsng]

@lucasmazza I updated the naming to skip_reconfirmation_in_callback (method and instance var). Would that fit better?

[ArneZsng]

@lucasmazza @ulissesalmeida Looks good to you now?

[ArneZsng]

@lucasmazza @ulissesalmeida Anything outstanding from your side?

[ulissesalmeida]

[lucasmazza]

@ArneZsng thanks for the patch, and sorry for the delay 😬