Doc - High-DPI support is now enabled by default in Chromium

Starting in M108 High-DPI support is now enabled by default in Chromium.

Additionally, as a refactor to move responsibility out of the embedder this change moves the existing EnableHighDPISupport calls in chrome_exe_main_win.cc into the respective GpuMain & BrowserMainRunnerImpl for the GPU & Browser processes.

https://github.com/chromiumembedded/cef/issues/3452