Add jsoncons

[TylerSeanRau]

I'm sure this is broken but there weren't instructions on how to test things are working before posting. Happy to debug if some more insight is given <3

[google-cla]

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[bazel-io]

Hello @bazelbuild/bcr-maintainers, modules without existing maintainers (jsoncons) have been updated in this PR. Please review the changes.

[meteorcloudy]

Please check: https://github.com/bazelbuild/bazel-central-registry/blob/main/docs/README.md#anonymous-module-test, you basically create a dummy module that depends on this one, and try to verify the targets build.

[meteorcloudy]

There is no debian12 support on Bazel CI yet..