build: fix MSVC ccache reporting

Fixes #31771

Summary

This PR resolves the incorrect reporting of ccache usage for MSVC builds by:

1. Removing forced compiler launcher configuration
2. Improving status message accuracy
3. Documenting proper MSVC+ccache workflows

Key Changes

• Deleted: cmake/ccache.cmake (Eliminates conflicts with user/CI configurations like sccache)
• Updated: CMakeLists.txt status reporting

  if(CMAKE_CXX_COMPILER_LAUNCHER)
    message(STATUS "Compiler launcher .............. ${CMAKE_CXX_COMPILER_LAUNCHER}")
  else()
    message(STATUS "Use ccache for compiling .............. NO")
  endif()

• Added Documentation:
  • Requires: Ninja generator
  • Configure: cmake -B build -G Ninja -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
  • Use: /Z7 debug flags (not /Zi)

Testing

# MSVC 2022 + Ninja
cmake -B build -G Ninja -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
cmake --build build
ccache -s  # Verified cache hits

# User override test
cmake -B build -DCMAKE_CXX_COMPILER_LAUNCHER=sccache  # No conflicts