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

Builds/CMake/RippledCore.cmake

@@ -108,6 +108,7 @@ target_sources (xrpl_core PRIVATE
   src/ripple/protocol/impl/STArray.cpp
   src/ripple/protocol/impl/STBase.cpp
   src/ripple/protocol/impl/STBlob.cpp
+  src/ripple/protocol/impl/STCurrency.cpp
   src/ripple/protocol/impl/STInteger.cpp
   src/ripple/protocol/impl/STLedgerEntry.cpp
   src/ripple/protocol/impl/STObject.cpp
@@ -566,6 +567,7 @@ target_sources (rippled PRIVATE
   src/ripple/app/tx/impl/CreateOffer.cpp
   src/ripple/app/tx/impl/CreateTicket.cpp
   src/ripple/app/tx/impl/DeleteAccount.cpp
+  src/ripple/app/tx/impl/DeleteOracle.cpp
   src/ripple/app/tx/impl/DepositPreauth.cpp
   src/ripple/app/tx/impl/DID.cpp
   src/ripple/app/tx/impl/Escrow.cpp
@@ -584,6 +586,7 @@ target_sources (rippled PRIVATE
   src/ripple/app/tx/impl/Remit.cpp
   src/ripple/app/tx/impl/SetAccount.cpp
   src/ripple/app/tx/impl/SetHook.cpp
+  src/ripple/app/tx/impl/SetOracle.cpp
   src/ripple/app/tx/impl/SetRemarks.cpp
   src/ripple/app/tx/impl/SetRegularKey.cpp
   src/ripple/app/tx/impl/SetSignerList.cpp
@@ -746,6 +749,7 @@ target_sources (rippled PRIVATE
   src/ripple/rpc/handlers/FetchInfo.cpp
   src/ripple/rpc/handlers/GatewayBalances.cpp
   src/ripple/rpc/handlers/GetCounts.cpp
+  src/ripple/rpc/handlers/GetAggregatePrice.cpp
   src/ripple/rpc/handlers/LedgerAccept.cpp
   src/ripple/rpc/handlers/LedgerCleanerHandler.cpp
   src/ripple/rpc/handlers/LedgerClosed.cpp
@@ -872,6 +876,7 @@ if (tests)
     src/test/app/NFTokenDir_test.cpp
     src/test/app/OfferStream_test.cpp
     src/test/app/Offer_test.cpp
+    src/test/app/Oracle_test.cpp
     src/test/app/OversizeMeta_test.cpp
     src/test/app/Path_test.cpp
     src/test/app/PayChan_test.cpp
@@ -1005,6 +1010,7 @@ if (tests)
     src/test/jtx/impl/AMMTest.cpp
     src/test/jtx/impl/Env.cpp
     src/test/jtx/impl/JSONRPCClient.cpp
+    src/test/jtx/impl/Oracle.cpp
     src/test/jtx/impl/TestHelpers.cpp
     src/test/jtx/impl/WSClient.cpp
     src/test/jtx/impl/hook.cpp
@@ -1143,6 +1149,7 @@ if (tests)
     src/test/rpc/DeliveredAmount_test.cpp
     src/test/rpc/Feature_test.cpp
     src/test/rpc/GatewayBalances_test.cpp
+    src/test/rpc/GetAggregatePrice_test.cpp
     src/test/rpc/GetCounts_test.cpp
     src/test/rpc/JSONRPC_test.cpp
     src/test/rpc/KeyGeneration_test.cpp