Arista 7260X3 Family (Update) (#1522)

device-types/Arista/DCS-7260CX3-64-F.yaml

device-types/Arista/DCS-7260CX3-64-R.yaml

device-types/Arista/DCS-7260CX3-64E-F.yaml

device-types/Arista/DCS-7260CX3-64E-R.yaml

module-types/Arista/PWR-1900-DC-F.yaml

module-types/Arista/PWR-1900-DC-R.yaml

module-types/Arista/PWR-1900AC-F.yaml

module-types/Arista/PWR-1900AC-R.yaml

module-types/Arista/PWR-745AC-F.yaml

module-types/Arista/PWR-745AC-R.yaml