Add two missing classes to async environment

doc/lua_api.md

@@ -6454,6 +6454,7 @@ This allows you easy interoperability for delegating work to jobs.
 ### List of APIs available in an async environment
 
 Classes:
+* `AreaStore`
 * `ItemStack`
 * `PerlinNoise`
 * `PerlinNoiseMap`

games/devtest/mods/unittests/inside_async_env.lua

@@ -10,6 +10,9 @@ local function do_tests()
 	assert(not core.object_refs)
 	-- stuff that should be here
 	assert(ItemStack)
+	local meta = ItemStack():get_meta()
+	assert(type(meta) == "userdata")
+	assert(type(meta.set_tool_capabilities) == "function")
 	assert(core.registered_items[""])
 	-- alias handling
 	assert(core.registered_items["unittests:steel_ingot_alias"].name ==

src/script/scripting_server.cpp

@@ -174,6 +174,8 @@ void ServerScripting::InitializeModApi(lua_State *L, int top)
 void ServerScripting::InitializeAsync(lua_State *L, int top)
 {
 	// classes
+	ItemStackMetaRef::Register(L);
+	LuaAreaStore::Register(L);
 	LuaItemStack::Register(L);
 	LuaPerlinNoise::Register(L);
 	LuaPerlinNoiseMap::Register(L);