Provider fee calculate based on duration and expiry calculate relative to block finalized timestamp

[soonhuat]

Is your feature request related to a problem? Please describe.
Provider fee validUntil might left very short duration if the network are congested which result to late block confirmation.
The provider fee is not a round number, because the moment market calculated the validUntil based on duration (example 10 minute) till request computed/calculated on Provider, time has elapsed and the duration from NOW to validUntil are lesser (lesser than 10 minute) and not the round duration anymore (example 1 OCEAN per minute for duration 10 minute is not 10 OCEAN, it is 9.998 OCEAN)

Describe the solution you'd like
To support provider fee calculation based on duration (as initializeCompute input parameter) as per minute basis.
The validity/expiry for the provider fee then calculate based on confirmed block timestamp + duration in timestamp during verification process.

Additional context
The provider fee have much accurate usable time after transaction confirmed.
The price of provider fee will always be round number based on the duration instead of validUntil (end time).