JSON incorrect object alignment in arrays with 64bit members

[pdgendt]

Describe the bug
Adding a 64bit member to a struct used for encoding/decoding in an array results in incorrect alignments, while looping the elements.

EDIT: Adding elements that are not in the object description are not supported, however adding a member to the description with a sizeof 8 still would not work.

See #59485 for changes

Tested on x86 64bit. I think the issue comes from the use of __alignof__ in include/zephyr/data/json.h, as the alignment will be fixed to 8 bytes. But the compiler still appears to use a 4 byte alignment.

To Reproduce
Steps to reproduce the behavior:

1. Checkout the PR branch
2. $ west build -p -b native_posix_64 -s tests/lib/json/
3. $ ./build/zephyr/zephyr.exe
4. See error

Expected behavior
Adding such a member should not impact json encoding/decoding.

Impact
This currently blocks PR #59485.

Logs and console output

$ ./build/zephyr/zephyr.exe
START - test_json_masked_obj_arr_decoding

    Assertion failed at WEST_TOPDIR/zephyr/tests/lib/json/src/main.c:924: lib_json_test_test_json_masked_obj_arr_decoding: (oa.num_elements not equal to 3)
Number of masked object fields not decoded correctly
 FAIL - test_json_masked_obj_arr_decoding in 0.000 seconds
===================================================================
START - test_json_masked_obj_arr_encoding

    Assertion failed at WEST_TOPDIR/zephyr/tests/lib/json/src/main.c:896: lib_json_test_test_json_masked_obj_arr_encoding: (ret not equal to 0)
Encoding array of masked object returned error
 FAIL - test_json_masked_obj_arr_encoding in 0.000 seconds

Environment (please complete the following information):

• OS: Linux (in WSL)
• Toolchain: zephyr SDK 0.15.0

[pdgendt]

A potential fix can be #53333

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.

[github-actions]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.