All those files are standalone programs that can be executed directly.
Some .py files were marked executable, others weren't, probably accidentally.
Mark them all as executable in preparation for subsequent changes.
The lists of directives for fuzzer tests are maintained manually in the
repo. There is a tools/check-directives.sh script that runs during test
phase and reports stale directive lists.
Let's rework the script into a generator so that these directive files
are created on-the-flight and needn't be updated whenever a unit file
directives change. The scripts is rewritten in Python to get rid of gawk
dependency and each generated file is a separate meson target so that
incremental builds refresh what is just necessary (and parallelize
(negligible)).
Note: test/fuzz/fuzz-unit-file/directives-all.slice is kept since there
is not automated way to generate it (it is not covered by the check
script neither).