Resources billed per hour should use `hours` as unit

[Seraf]

On the JSON generated by Terracost, some resources like aws_instance are not correctly computed.
The cost result is correct, but there's a miss on quantity and unit attributes:

{
   "planned_cost":"121.336",
   "planned_hourly_cost":"0.166214",
   "prior_cost":"0",
   "prior_hourly_cost":"0",
   "resource_estimates":[
      {
         "address":"module.nexus.aws_instance.nexus",
         "components":[
            {
               "label":"Compute",
               "planned":{
                  "cost":"119.136",
                  "details":[
                     "Linux",
                     "on-demand",
                     "t3a.xlarge"
                  ],
                  "hourly_cost":"0.1632",
                  "quantity":1
               },
               "rate":"119.136"
            },
            {
               "label":"Root volume: Storage",
               "planned":{
                  "cost":"2.2",
                  "details":[
                     "gp2"
                  ],
                  "hourly_cost":"0.003014",
                  "quantity":20
               },
               "rate":"0.11",
               "unit":"GB"
            }
         ],
         "planned_cost":"121.336",
         "planned_hourly_cost":"0.166214",
         "prior_cost":"0",
         "prior_hourly_cost":"0",
         "provider":"aws",
         "type":"aws_instance"
      }
   ],
}

On this example, the rate, quantity and unit should be calculated in terms of hours, using 730 as quantity instead of considering 1 instance as a quantity. Users are not buying an instance, but an amount of hour of an instance.