Remove GetProcAddress to TF_CreateCategoryMgr

This is a preparation to remove the dependency on CoCreateInstance from
mozc_tip{32,64}.dll to comply with GUID_TFCAT_TIPCAP_COMLESS (google#837).

With my previous commit [1], we now create an import library for
msctf.dll as part of our build process.  With this commit,
mozc_tip{32,64}.dll actually start importing TF_CreateCategoryMgr from
msctf.dll in an implicit manner.  This should be safer and more
efficient than relying on GetProcAddress as long as the API in question
is guaranteed to exist.

Note that we have already done the same optimization for input.dll [2].

There should be no user observable behavior change.

#codehealth

 [1]: 006084c
 [2]: f470414

PiperOrigin-RevId: 576674633

src/win32/tip/BUILD.bazel

@@ -150,6 +150,7 @@ mozc_cc_library(
         "//base/win32:hresult",
         "//base/win32:hresultor",
         "//protocol:commands_cc_proto",
+        "//win32/base:msctf_dll",
         "//win32/base:win32_window_util",
         "@com_google_absl//absl/base",
         "@com_google_absl//absl/container:flat_hash_map",

src/win32/tip/tip.gyp

@@ -108,6 +108,7 @@
             '../base/win32_base.gyp:ime_base',
             '../base/win32_base.gyp:ime_impl_base',
             '../base/win32_base.gyp:imframework_util',
+            '../base/win32_base.gyp:msctf_dll_import_lib',
             '../base/win32_base.gyp:text_icon',
           ],
         },

src/win32/tip/tip_text_service.cc

@@ -240,18 +240,8 @@ void EnsureKanaLockUnlocked() {
 
 // A COM-independent way to instantiate Category Manager object.
 wil::com_ptr_nothrow<ITfCategoryMgr> GetCategoryMgr() {
-  const HMODULE module = WinUtil::GetSystemModuleHandle(L"msctf.dll");
-  if (module == nullptr) {
-    return nullptr;
-  }
-  const auto tf_create_tegory_mgr =
-      reinterpret_cast<decltype(&TF_CreateCategoryMgr)>(
-          GetProcAddress(module, "TF_CreateCategoryMgr"));
-  if (tf_create_tegory_mgr == nullptr) {
-    return nullptr;
-  }
   wil::com_ptr_nothrow<ITfCategoryMgr> ptr;
-  return SUCCEEDED(tf_create_tegory_mgr(&ptr)) ? ptr : nullptr;
+  return SUCCEEDED(TF_CreateCategoryMgr(&ptr)) ? ptr : nullptr;
 }
 
 // Custom hash function for wil::com_ptr_nothrow.