[Yang] Fix Yang model of BGP Allowed Prefix (sonic-net#20550)

Why I did it
Bugfix for Yang model of BGP Allowed Prefix.

Support optional NEIGHBOR_TYPE in key.
Support optional le and ge in prefixes_v4/prefixes_v6 list (e.g., 10.20.30.0/24 le 30).
Work item tracking
Microsoft ADO (number only): 30001113
How I did it
Updated sonic-bgp-allowed-prefix.yang.

Define optional value NEIGHBOR_TYPE in key.
Define type bgp-allowed-ipv4-prefix and bgp-allowed-ipv6-prefix to support the optional suffix in prefixes_v4/prefixes_v6 list.
How to verify it
Verified by UT:

Author: lizhijianrd

src/sonic-yang-models/tests/yang_model_tests/tests/bgp.json

@@ -158,43 +158,32 @@
     "BGP_PEERRANGE_ALL_VALID": {
         "desc": "Configure BGP peer range table."
     },
-    "BGP_ALLOWED_PREFIXES_COM_LIST_ALL_VALID": {
+    "BGP_ALLOWED_PREFIXES_ALL_VALID": {
         "desc": "Configue BGP allowed prefix list."
     },
-    "BGP_ALLOWED_PREFIXES_COM_LIST_INVALID_DEPLOYMENT": {
-        "desc": "Invalid default action.",
+    "BGP_ALLOWED_PREFIXES_INVALID_DEPLOYMENT": {
+        "desc": "Invalid deployment.",
         "eStrKey" : "Pattern"
     },
-    "BGP_ALLOWED_PREFIXES_COM_LIST_INVALID_DEFAULT_ACTION": {
-        "desc": "Invalid default action.",
+    "BGP_ALLOWED_PREFIXES_INVALID_ID": {
+        "desc": "Invalid id.",
         "eStrKey" : "InvalidValue",
-        "eStr" : ["default_action"]
-    },
-    "BGP_ALLOWED_PREFIXES_COM_LIST_INVALID_PREFIXES_IPV4": {
-        "desc": "Invalid IPv4 prefix.",
-        "eStrKey" : "Pattern"
+        "eStr" : ["id"]
     },
-    "BGP_ALLOWED_PREFIXES_COM_LIST_INVALID_PREFIXES_IPV6": {
-        "desc": "Invalid IPv6 prefix.",
-        "eStrKey" : "Pattern"
-    },
-    "BGP_ALLOWED_PREFIXES_LIST_ALL_VALID": {
-        "desc": "Configue BGP allowed prefix list."
-    },
-    "BGP_ALLOWED_PREFIXES_LIST_INVALID_DEPLOYMENT": {
-        "desc": "Invalid default action.",
+    "BGP_ALLOWED_PREFIXES_INVALID_NEIGHBOR": {
+        "desc": "Invalid neighbor.",
         "eStrKey" : "Pattern"
     },
-    "BGP_ALLOWED_PREFIXES_LIST_INVALID_DEFAULT_ACTION": {
+    "BGP_ALLOWED_PREFIXES_INVALID_DEFAULT_ACTION": {
         "desc": "Invalid default action.",
         "eStrKey" : "InvalidValue",
         "eStr" : ["default_action"]
     },
-    "BGP_ALLOWED_PREFIXES_LIST_INVALID_PREFIXES_IPV4": {
+    "BGP_ALLOWED_PREFIXES_INVALID_PREFIXES_IPV4": {
         "desc": "Invalid IPv4 prefix.",
         "eStrKey" : "Pattern"
     },
-    "BGP_ALLOWED_PREFIXES_LIST_INVALID_PREFIXES_IPV6": {
+    "BGP_ALLOWED_PREFIXES_INVALID_PREFIXES_IPV6": {
         "desc": "Invalid IPv6 prefix.",
         "eStrKey" : "Pattern"
     },