Refactor handler to external

Moved task handler functions to external functions, signatures are in
tasks.h, each function has its own .c file in Src/tasks

STM32/CM7/Core/Inc/tasks.h

@@ -0,0 +1,7 @@
+// Copyright (C) 2026 Hector van der Aa <hector@h3cx.dev>
+// Copyright (C) 2026 Pierre Barbier <pierrebarbier741@gmail.com>
+// Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+void crankHandler(void *argument);
+void camHandler(void *argument);