[llvm] [DirectX] Add boilerplate integration of `objcopy` for `DXContainerObjectFile` (PR #153079)

[James Henderson via llvm-commits]

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@@ -0,0 +1,46 @@
+## Check that llvm-objcopy reports a suitable error when it
+## encounters an invalid input during reading. The purpose is not to have
+## extensive of all read errors, that should be done in DXContainerTest.cpp,
+## instead this is a sanity check that the error is produced when using the
+## reader in llvm-objcopy.
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jh7370 wrote:

The first sentence of this comment is fine. The rest probably is unneeded, as it should be the way things work in general.

https://github.com/llvm/llvm-project/pull/153079