Merge branch 'selftests/bpf: test_progs can read test lists from file'

Stephen Veiss says:

====================

BPF selftests have ALLOWLIST and DENYLIST files, used to control which
tests are run in CI. These files are currently parsed by a shell
script. [1]

This patchset allows those files to be specified directly on the
test_progs command line (eg, as -a @ALLOWLIST).

This also fixes a bug in the existing test filter code causing
unnecessary duplicate top-level test filter entries to be created.

[1] https://github.com/kernel-patches/vmtest/blob/57feb460047b69f891cf4afe3cc860794a2ced17/ci/vmtest/run_selftests.sh#L21-L27
---

v2:
 - error handling style changes per reviewer comments
 - fdopen return value checking in test_parse_test_list_file

v1:
 https://lore.kernel.org/bpf/20230425225401.1075796-1-sveiss@meta.com/
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>