Restore ActiveRecord states after a rollback for models w/o callbacks

This fixes a regression (#13744) that was caused by 67d8bb9.

In 67d8bb9, we introduced lazy rollback for records, such that the
record's internal states and attributes are not restored immediately
after a transaction rollback, but deferred until they are first
accessed.

This optimization is only performed when the model does not have any
transactional callbacks (e.g. `after_commit` and `after_create`).

Unfortunately, the models used to test the affected codepaths all
comes with some sort of transactional callbacks. Therefore this
codepath remains largely untested until now and as a result there are
a few issues in the implementation that remains hidden until now.

First, the `sync_with_transaction_state` (or more accurately,
`update_attributes_from_transaction_state`) would perform the
synchronization prematurely before a transaction is finalized (i.e.
comitted or rolled back). As a result, when the actuall rollback
happens, the record will incorrectly assumes that its internal states
match the transaction state, and neglect to perform the restore.

Second, `update_attributes_from_transaction_state` calls `committed!`
in some cases. This in turns checks for the `destroyed?` state which
also requires synchronization with the transaction stae, which causes
an infnite recurrsion.

This fix works by deferring the synchronization until the transaction
has been finalized (addressing the first point), and also unrolled
the `committed!` and `rolledback!` logic in-place (addressing the
second point).

It should be noted that the primary purpose of the `committed!` and
`rolledback!` methods are to trigger the relevant transactional
callbacks. Since this code path is only entered when there are no
transactional callbacks on the model, this shouldn't be necessary. By
unrolling the method calls, the intention here (to restore the states
when necessary) becomes more clear.
Merge pull request #13751 from chancancode/ar_rollback_fix

Restore ActiveRecord states after a rollback for models w/o callbacks
Ensure #second acts like #first AR finder
This commit bring the famous ordinal Array instance methods defined
in ActiveSupport into ActiveRecord as fully-fledged finders.

These finders ensure a default ascending order of the table's primary
key, and utilize the OFFSET SQL verb to locate the user's desired
record. If an offset is defined in the query, calling #second adds
to the offset to get the actual desired record.