lnrpc: add imputed costs proto definitions

- Add experimental imputed costs API to router service with three new RPCs:
  XImportImputedCosts, XQueryImputedCosts, XDeleteImputedCosts.
- Introduces ImputedCostNamespace, ImputedCostPair, ImputedCostPolicy messages
  with support for success-based and attempt-based cost calculations.
- Adds imputed_cost_restrictions field to SendPaymentRequest and QueryRoutesRequest
  for total routing cost limits.
- Compiling of the protos
- Update router.yaml

Author: feelancer21

lnrpc/lightning.pb.go

@@ -3207,6 +3207,11 @@ message QueryRoutesRequest {
     channel may be used.
     */
     repeated uint64 outgoing_chan_ids = 20;
+
+    /*
+    An optional restriction to limit routing fees and imputed costs.
+    */
+    ImputedCostRestriction imputed_cost_restrictions = 21;
 }
 
 message NodePair {
@@ -3236,6 +3241,19 @@ message EdgeLocator {
     bool direction_reverse = 2;
 }
 
+message ImputedCostRestriction {
+    /*
+    The name of the namespace for calculating the imputed costs.
+    */
+    string namespace = 1;
+
+    /*
+    The maximum number of millisatoshis that may be incurred, including routing
+    fees and imputed costs.
+    */
+    int64 total_cost_limit_msat = 2;
+}
+
 message QueryRoutesResponse {
     /*
     The route that results from the path finding operation. This is still a

lnrpc/lightning.proto

@@ -1511,6 +1511,21 @@
               "format": "uint64"
             },
             "collectionFormat": "multi"
+          },
+          {
+            "name": "imputed_cost_restrictions.namespace",
+            "description": "The name of the namespace for calculating the imputed costs.",
+            "in": "query",
+            "required": false,
+            "type": "string"
+          },
+          {
+            "name": "imputed_cost_restrictions.total_cost_limit_msat",
+            "description": "The maximum number of millisatoshis that may be incurred, including routing\nfees and imputed costs.",
+            "in": "query",
+            "required": false,
+            "type": "string",
+            "format": "int64"
           }
         ],
         "tags": [
@@ -1662,6 +1677,10 @@
                     "format": "uint64"
                   },
                   "description": "The channel ids of the channels allowed for the first hop. If empty, any\nchannel may be used."
+                },
+                "imputed_cost_restrictions": {
+                  "$ref": "#/definitions/lnrpcImputedCostRestriction",
+                  "description": "An optional restriction to limit routing fees and imputed costs."
                 }
               }
             }
@@ -5578,6 +5597,20 @@
         }
       }
     },
+    "lnrpcImputedCostRestriction": {
+      "type": "object",
+      "properties": {
+        "namespace": {
+          "type": "string",
+          "description": "The name of the namespace for calculating the imputed costs."
+        },
+        "total_cost_limit_msat": {
+          "type": "string",
+          "format": "int64",
+          "description": "The maximum number of millisatoshis that may be incurred, including routing\nfees and imputed costs."
+        }
+      }
+    },
     "lnrpcInboundFee": {
       "type": "object",
       "properties": {