[llvm] [DirectX] Add `extract-section` to `llvm-objcopy` and implement it for `DXContainer` (PR #154804)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Please update the docs with the new option.

Please note that I am off for much of next week and may not have time to review this further for a week or two.

https://github.com/llvm/llvm-project/pull/154804