M123: Update OOPPD GDI metafile handling for PostScript

Relocate the PostScriptMetafile class out from the anonymous scope of
PDF converter implementation and make it a public class.  This enables
the Print Backend service to use that when appropriate for print jobs
where the conversion was made to store PostScript data inside of an EMF
wrapper.  Include some style corrections to the code as well.

Update PostScriptMetafile to override GetDataType(), to signify that
its data is a different type of EMF object compared to what is handled
by the base class.

Using the correct EMF class for the data ensures that the correct
playback method is used against the data, so that the desired imaging
is achieved.  This allows the test expectations for
SystemAccessProcessSandboxedServicePrintBrowserTest to similarly
succeed for all printer language types.

(cherry picked from commit d03e5918c6acd61aff60c66a521b6b8c328bc30c)

Bug: 41492268
Change-Id: I5dfddff94dfad9b65f5cc4f39496d372e6a607b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5331976
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Alan Screen <awscreen@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1268742}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5362284
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/6312@{#539}
Cr-Branched-From: 6711dcdae48edaf98cbc6964f90fac85b7d9986e-refs/heads/main@{#1262506}

• chrome/browser/printing/pdf_to_emf_converter.cc[diff]
• chrome/browser/printing/system_access_process_print_browsertest.cc[diff]
• chrome/services/printing/print_backend_service_impl.cc[diff]
• printing/emf_win.cc[diff]
• printing/emf_win.h[diff]