[9.20] chg: dev: Support compilation with cmocka 2.0.0+

The `assert_in_range()` function was deprecated in favor of
`assert_int_in_range()` and `assert_uint_in_range()`. Add compatibility
shims for cmocka<2.0.0 and use the new functions.

Closes #5699

Backport of MR !11412

Merge branch 'backport-5699-support-cmocka-2.0.0-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!11437