[dmeijboom]

Both the PHP 7.2 and 7.4 manifests request their JSON packages and the image configuration enables them, but neither lockfile includes the packages. This leaves the images without the JSON extension.

Add the missing JSON package entries for amd64 and arm64, matching the pinned PHP common package versions. Existing package entries and pins remain unchanged.

Validation:

• Downloaded all four JSON packages and verified their SHA-256 against the current Sury package indexes.
• Verified all added dependency keys resolve to existing locked packages.
• Executed JSON extension loading and encode/decode round trips using the pinned PHP 7.2 and 7.4 CLI binaries on amd64; both passed.
• Confirmed the packages contain the json.so and json.ini paths used by the image configuration.
• git diff --check passed.

Full Bazel image builds could not run locally because the Bazel JVM cannot validate the bcr.bazel.build TLS certificate. ARM64 runtime execution was not performed; image builds require CI verification.