Check format of vcpkg.json file in x-add-version

[autoantwort]

The x-add-version command already checks if there are vcpkg.json file changes that are not committed. I should also check if the vcpkg.json file is well formatted.

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Is your feature request related to a problem? Please describe.
I use VS Code to edit the vcpkg.json files, but when I save a plugin formats the json file, but in an incompatible format to vcpkg (4 spaces indention). Often I forgot about that, commit the changes, run vcpkg x-add-version ..., commit and push the changes. After a few minutes I see the failure in the pipeline.

Proposed solution
Check if the vcpkg.json file is whell formatted when running vcpkg x-add-version ...