Allow Sieve numeric matches on JSONDict children

[BharatDeva]

Fixes #2599

Summary

This updates Sieve numeric-match validation so fields below harmonization entries typed as JSONDict are not rejected during static validation.

For example, extra is typed as JSONDict, so a Sieve rule such as:

if extra.min_amplification > 5 {
    ...
}

should be allowed to parse and then be evaluated at runtime against the event value.

Known harmonized fields are still statically checked against the existing numeric-compatible types.

Testing

INTELMQ_ROOT_DIR=/mnt/c/Users/bhara/OneDrive/Desktop/Python/intelmq/intelmq \
INTELMQ_TEST_EXOTIC=1 \
PYTHONPATH=. \
python -m unittest intelmq.tests.bots.experts.sieve.test_expert

Result:

Ran 61 tests in 10.918s

OK

Additional checks:

git diff --check
python -m compileall -q intelmq/bots/experts/sieve/expert.py intelmq/tests/bots/experts/sieve/test_expert.py