[Viz] Add CanCreateNativePixmap() to SharedImageManager

This CL hides the goop that checks for successful creation of a
NativePixmap with the given format/usage in
GpuServiceImpl::IsGMBNV12Supported() behind SharedImageManager. It's
unfortunately not feasible to move the method wholesale due to the
call to GpuServiceImpl::IsNativeBufferSupported().

Note: `shared_image_manager()` is guaranteed to be non-null as all
callers of `InitializeWithHostInternal()` create it internally if
needed before passing it in.

Bug: 404905709
Change-Id: I3715ec08ea218a47480b7468f686381e9ce2bfbc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6810905
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1509082}