[MSCTF] Make ITfLangBarMgr C++ (reactos#8056)

Implementing missing features...
JIRA issue: CORE-19361
- Delete langbarmgr.c (C) and add
  langbarmgr.cpp (C++).
- Remove the legacy C
  implementation of ITfLangBarMgr.
- Add CLangBarMgr class.

Author: katahiromz

base/ctf/msctf/CMakeLists.txt

@@ -11,14 +11,14 @@ list(APPEND SOURCE
     displayattributemgr.c
     documentmgr.c
     inputprocessor.c
-    langbarmgr.c
     msctf.c
     range.c
     threadmgr.c
     precomp.h
     ${CMAKE_CURRENT_BINARY_DIR}/msctf_stubs.c)
 
 list(APPEND PCH_SKIP_SOURCE
+    langbarmgr.cpp
     mlng.cpp
     utils.cpp)