Candidate window may be misplaced when Per-Monitor DPI setting is enabled in Windows

[yukawa]

Description

When Mozc is used under Per-Monitor DPI environment where each display has different effective DPI, Mozc's candidate window may not be shown at the expected location.

This is a sub task of the following effort.

• https://github.com/google/mozc/issues/831

Steps to reproduce

1. Build and install Mozc into multi-display environment, where each display is configured to have different effective DPI
2. Open a notepad in secondary display
3. Select Mozc and enable it.
4. Type "tesuto"

Expected behavior

• At the step 4, Mozc's suggestion window is placed just below the composing text.

Actual behavior

• At the step 4, Mozc's suggestion window is placed of the place from the composing text.

Screenshots

Version or commit-id

af209061632ba7dcc64b63bd06eb988974375508

Environment

• OS: OS: Windows 11 22H2
• Related Applications: Any