fix: use abi.encode for hashing arrays (XMTP-10) (#165)

Change hashing of nodeIds_ to use abi.encode in PayerReportManager to address XMTP-10
This pull request updates the hashing logic in the PayerReportManager contract to use abi.encode for nodeIds_ when computing the keccak256 that combines endSequenceId_, endMinuteSinceEpoch_, payersMerkleRoot_, and the nodeIds_ hash. It also updates unit tests to reflect the new computed values.

Modify PayerReportManager to replace abi.encodePacked(nodeIds_) with abi.encode(nodeIds_) in the hash computation in PayerReportManager.sol
Update three expected bytes32 constants in tests to match the new hash results in PayerReportManager.t.sol

Author: deluca-mike

src/settlement-chain/PayerReportManager.sol

@@ -374,7 +374,7 @@ contract PayerReportManager is IPayerReportManager, Initializable, Migratable, E
                         endSequenceId_,
                         endMinuteSinceEpoch_,
                         payersMerkleRoot_,
-                        keccak256(abi.encodePacked(nodeIds_))
+                        keccak256(abi.encode(nodeIds_))
                     )
                 )
             );

test/unit/PayerReportManager.t.sol

@@ -1186,7 +1186,7 @@ contract PayerReportManagerTests is Test {
                 payersMerkleRoot_: bytes32(uint256(5)),
                 nodeIds_: new uint32[](6)
             }),
-            0xe95b9352b7afb9da83952cce75aba1d466ed7daeafc009c1964b85b8fe08bc09
+            0xdde54243da83f4b7c3fa535080f6cd0441fda0649edb15d95551f895a3529dfc
         );
 
         assertEq(
@@ -1198,7 +1198,7 @@ contract PayerReportManagerTests is Test {
                 payersMerkleRoot_: bytes32(uint256(50)),
                 nodeIds_: new uint32[](60)
             }),
-            0x1dcb9deef4cebf9e13169296e27dee6166ed09af01b62f5c65dff9b3a9afb82d
+            0xb70f0c64254571c8cc5f6a84339bae9a135744d1f8059a3908121c95b40529f7
         );
     }
 
@@ -1222,7 +1222,7 @@ contract PayerReportManagerTests is Test {
                 payersMerkleRoot_: payersMerkleRoot_,
                 nodeIds_: nodeIds_
             }),
-            0x79f316f2836745161f3020e431db382ce57aab339df1429de068a62bf940295b
+            0x68e2a926d1e4309c70d546f976fc17eacc87d245862ad8a5d9c80b86e1dd4d61
         );
     }