bug(events): update the ApiEventsType for PaymentsSessionResponse to use payments flow

[lsampras]

update the ApiEventMetric trait for this response to return ApiEventsType::Payment { payment_id : String} variant.
based on the payment id stored in its body

This would help for better structuring and help list this api call in the dashboard events as well

[tanbirali]

I am interested

[aayushdhiman01]

I would like to work on this issue.

[lsampras]

Assigning this issue to @tanbirali since he asked first.
@aayushdhiman01 you can take a look at similar open issues. (maybe take a look at #4525 )