Grouped the buffers from GDB's flash write packets so that we only flush once we have the full buffer.

This fixes an issue with GDB programming, where it was sending misaligned buffers and program memory
wasn't being properly updated.

src/DebugServer/Gdb/DebugSession.hpp

@@ -1,10 +1,12 @@
 #pragma once
 
 #include <cstdint>
+#include <optional>
 
 #include "TargetDescriptor.hpp"
 #include "Connection.hpp"
 #include "Feature.hpp"
+#include "ProgrammingSession.hpp"
 
 namespace Bloom::DebugServer::Gdb
 {
@@ -33,6 +35,21 @@ namespace Bloom::DebugServer::Gdb
          */
         bool waitingForBreak = false;
 
+        /**
+         * When the user attempts to program the target via GDB's 'load' command, GDB will send a number of
+         * FlashWrite (vFlashWrite) packets to Bloom. We group the data in these packets and flush it all at once, upon
+         * receiving a FlashDone (vFlashDone) packet.
+         *
+         * The grouped data is held in a ProgrammingSession object, against the active debug session. Once the data has
+         * been flushed, the ProgrammingSession object is destroyed.
+         *
+         * See the ProgrammingSession struct and GDB RSP documentation for more.
+         *
+         * This member holds the current (if any) ProgrammingSession object. It should only be populated during
+         * programming.
+         */
+        std::optional<ProgrammingSession> programmingSession = std::nullopt;
+
         DebugSession(
             Connection&& connection,
             const std::set<std::pair<Feature, std::optional<std::string>>>& supportedFeatures,