Implement Allocator wrapper for memory context

mem/src/ctx/mem_ctx.c

@@ -16,6 +16,11 @@ internal MemCTX g_context = {0};
 
 internal Arena *get_arena(CTXDestBuffer buffer);
 
+Allocator wapp_mem_ctx_allocator(CTXDestBuffer buffer) {
+  Arena *arena = get_arena(buffer);
+	return wapp_mem_arena_allocator(arena);
+}
+
 void wapp_mem_ctx_init(u64 main_buf_capacity, u64 temp_buf_capacity) {
   g_context.main_initialised =
       wapp_mem_arena_init(&g_context.main, main_buf_capacity);