Main Menu: Add get_clientmodpath API (#5912)

Add `core.get_clientmodpath` to main menu API (also possible in async calls).

doc/menu_lua_api.txt

@@ -35,6 +35,8 @@ core.get_builtin_path()
 ^ returns path to builtin root
 core.get_modpath() (possible in async calls)
 ^ returns path to global modpath
+core.get_clientmodpath() (possible in async calls)
+^ returns path to global client-side modpath
 core.get_modstore_details(modid) (possible in async calls)
 ^ modid numeric id of mod in modstore
 ^ returns {
@@ -234,7 +236,7 @@ Limitations of Async operations
  -Limited set of available functions
 	e.g. No access to functions modifying menu like core.start,core.close,
 	core.file_open_dialog
-			
+
 
 Class reference
 ----------------

src/script/lua_api/l_mainmenu.cpp

@@ -734,6 +734,15 @@ int ModApiMainMenu::l_get_modpath(lua_State *L)
 	return 1;
 }
 
+/******************************************************************************/
+int ModApiMainMenu::l_get_clientmodpath(lua_State *L)
+{
+	std::string modpath = fs::RemoveRelativePathComponents(
+		porting::path_user + DIR_DELIM + "clientmods" + DIR_DELIM);
+	lua_pushstring(L, modpath.c_str());
+	return 1;
+}
+
 /******************************************************************************/
 int ModApiMainMenu::l_get_gamepath(lua_State *L)
 {
@@ -1120,6 +1129,7 @@ void ModApiMainMenu::Initialize(lua_State *L, int top)
 	API_FCT(set_topleft_text);
 	API_FCT(get_mapgen_names);
 	API_FCT(get_modpath);
+	API_FCT(get_clientmodpath);
 	API_FCT(get_gamepath);
 	API_FCT(get_texturepath);
 	API_FCT(get_texturepath_share);
@@ -1150,6 +1160,7 @@ void ModApiMainMenu::InitializeAsync(lua_State *L, int top)
 	API_FCT(get_favorites);
 	API_FCT(get_mapgen_names);
 	API_FCT(get_modpath);
+	API_FCT(get_clientmodpath);
 	API_FCT(get_gamepath);
 	API_FCT(get_texturepath);
 	API_FCT(get_texturepath_share);
@@ -1162,4 +1173,3 @@ void ModApiMainMenu::InitializeAsync(lua_State *L, int top)
 	API_FCT(get_modstore_list);
 	//API_FCT(gettext); (gettext lib isn't threadsafe)
 }
-

src/script/lua_api/l_mainmenu.h

@@ -108,6 +108,8 @@ private:
 
 	static int l_get_modpath(lua_State *L);
 
+	static int l_get_clientmodpath(lua_State *L);
+
 	static int l_get_gamepath(lua_State *L);
 
 	static int l_get_texturepath(lua_State *L);