id: Fix incorrect human-readable output

[frendsick]

This PR fixes the human-readable output of the -p flag. Currently, it reports incorrect information about euid and does not include rgid when it differs from egid.

Reproduction instructions can be found in the related issue #7812.

fixes #7812

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[frendsick]

Testing this has the same problem as #7796. The test would need to be run with elevated privileges and change the EUID and EGID of the process to be different from the actual UID and GID.
See: #7796 (comment)

[sylvestre]

how can i test this locally ? :)

[frendsick]

See the Reproduce section in the related issue #7812. The main branch prints the wrong output while this branch should print the expected output.

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[frendsick]

The test_id_pretty_print_suid_binary test can be run by enabling the chmod and chown features. To test the output with different EUID and EGID values than the real UID and GID, you can use the following command:

sudo true && cargo test --features id,chown,chmod test_id_pretty_print_suid_binary

The sudo true command enables running commands with sudo without a password within the test, assuming the sudo's timestamp_timeout is not configured to 0 (always prompt for a password).

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[frendsick]

@sylvestre This PR is ready for review.

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