[llvm] [llvm-readobj][COFF] Add JSON Output Style (PR #95074)

[Miguel A. Arroyo via llvm-commits]

mayanez wrote:

I've gone ahead with splitting this PR's commits while we continue our discussion. Hopefully the split makes the changes easier to parse. 

Additionally, I've:
* integrated the tests into the relevant `*.test` files instead of creating the `*-json.test` variants as suggested.
* updated the Release Notes & `llvm-readobj` docs. I purposefully grouped it with the `--coff-output-style` for now pending any final conclusions about the generic flag.




https://github.com/llvm/llvm-project/pull/95074