Price Oracle (XLS-47d): (#4789) (#4789)

Implement native support for Price Oracles.

 A Price Oracle is used to bring real-world data, such as market prices,
 onto the blockchain, enabling dApps to access and utilize information
 that resides outside the blockchain.

 Add Price Oracle functionality:
 - OracleSet: create or update the Oracle object
 - OracleDelete: delete the Oracle object

 To support this functionality add:
 - New RPC method, `get_aggregate_price`, to calculate aggregate price for a token pair of the specified oracles
 - `ltOracle` object

 The `ltOracle` object maintains:
 - Oracle Owner's account
 - Oracle's metadata
 - Up to ten token pairs with the scaled price
 - The last update time the token pairs were updated

 Add Oracle unit-tests

src/ripple/protocol/impl/ErrorCodes.cpp

@@ -112,7 +112,8 @@ constexpr static ErrorInfo unorderedErrorInfos[]{
     {rpcTXN_NOT_FOUND,          "txnNotFound",          "Transaction not found.", 404},
     {rpcNAMESPACE_NOT_FOUND,    "namespaceNotFound",    "Namespace not found.", 404},
     {rpcUNKNOWN_COMMAND,        "unknownCmd",           "Unknown method.", 405},
-    {rpcLEDGER_MISSING,         "ledgerMissing",        "One or more ledgers in the specified range is missing", 406}};
+    {rpcLEDGER_MISSING,         "ledgerMissing",        "One or more ledgers in the specified range is missing", 406},
+    {rpcORACLE_MALFORMED,       "oracleMalformed",      "Oracle request is malformed.", 400}};
 // clang-format on
 
 // Sort and validate unorderedErrorInfos at compile time.  Should be