Generate MachO format dumps by the MacOS createdump

[mikem8361]

Currently createdump generates ELF core dumps on MacOS. We need to develop a MachO dump writer for the VS for Mac conversion to .NET Core.

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Issue Details

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Currently createdump generates ELF core dumps on MacOS. We need to develop a MachO dump writer for the VS for Mac conversion to .NET Core.

Author:	mikem8361
Assignees:	mikem8361
Labels:	area-Diagnostics-coreclr, enhancement
Milestone:	-