`apstra_rack_type` resource should honor or enforce caller's capitalization

[chrismarget-j]

Right now, this configuration:

resource "apstra_rack_type" "a" {
  name                       = "_demo w/3 servers"
  fabric_connectivity_design = "l3collapsed"
  leaf_switches = {
    "leaf" = {
      logical_device_id   = "AOS-7x10-Leaf"
      redundancy_protocol = "esi"
    }
  }
  generic_systems = {
    "single" = {
      count = 1
      logical_device_id = "AOS-1x10-1"
      links = {
        "leaf" = {
          count = 1
          speed = "10G"
          target_switch_name = "leaf"
          switch_peer = "first"
        }
      }
    }
  }
}

Produces this result:

│ Error: Provider produced inconsistent result after apply
│ 
│ When applying changes to apstra_rack_type.a, provider "provider[\"registry.terraform.io/juniper/apstra\"]" produced an unexpected new value: .generic_systems["single"].links["leaf"].speed: was
│ cty.StringVal("10g"), but now cty.StringVal("10G").
│ 
│ This is a bug in the provider, which should be reported in the provider's own issue tracker.

Maybe use a case insensitive string custom type?