Add support for QSFP56 and QSFP56_DD_TYPE3 form factor identities

QSFP56_DD transceiver form-factor encompasses more variants
than just type1 (8 optical signals) and type2 (4 optical signals)
defined in OpenConfig. Adding QSFP_DD_TYPE3 (1 optical signal)
form-factor identity.

QSFP56 form-factor identity is also added because it's missing.

release/models/optical-transport/openconfig-transport-types.yang

@@ -22,7 +22,13 @@ module openconfig-transport-types {
     "This module contains general type definitions and identities
     for optical transport models.";
 
-  oc-ext:openconfig-version "0.19.0";
+  oc-ext:openconfig-version "0.20.0";
+
+  revision "2023-07-25" {
+    description
+      "Add QSFP56 and QSFP56_DD_TYPE3 form factor identity.";
+    reference "0.20.0";
+  }
 
   revision "2023-07-24" {
     description
@@ -824,6 +830,13 @@ module openconfig-transport-types {
       channels";
   }
 
+  identity QSFP56 {
+    base TRANSCEIVER_FORM_FACTOR_TYPE;
+    description
+      "QSFP pluggable optic with support for up to 4x56G physical
+      channels";
+  }
+
   identity QSFP56_DD_TYPE1 {
     base TRANSCEIVER_FORM_FACTOR_TYPE;
     description
@@ -839,6 +852,14 @@ module openconfig-transport-types {
       signals.";
   }
 
+  identity QSFP56_DD_TYPE3 {
+    base TRANSCEIVER_FORM_FACTOR_TYPE;
+    description
+      "QSFP DD pluggable optic with support for 1x448G physical
+      channel. Type 3 uses one optical and eight electrical
+      signals.";
+  }
+
   identity CPAK {
     base TRANSCEIVER_FORM_FACTOR_TYPE;
     description