Learn the file-IO graph without root, using strace

[sawenzel]

This makes the file-IO-graph learning pluggable and adds an strace backend, so a pilot run no longer needs a binary with CAP_SYS_ADMIN. The graph it produces is the one --remove-files-early already reads back.

• The runner gains --filegraph-backends. Naming several at once runs them side by side, which is how they are compared. O2DPG_PRODUCE_FILEGRAPH still selects fanotify and names its monitor.
• The strace backend wraps each task command, so a file access is attributed by the trace it lands in rather than by walking /proc after the event. --seccomp-bpf keeps the cost at about 59 us per traced open; the backend probes for it.
• filegraph_report.py holds the exclusion rules, the ./tfN -> ./tfX templating, the JSON schema and the graphviz rendering, so the two analysers cannot drift. analyse_FileIO_v2.py reproduces its previous output byte for byte.
• compare_reports.py grades one report against another. A missing edge deletes a file a later task still reads; an extra edge only delays the deletion. The verdicts EXACT, SAFE and UNSAFE follow that asymmetry.
• tests/equivalence_test.py runs a workflow whose graph is known by construction and grades every backend against it, in seconds and with no ALICE software. strace comes out EXACT.
• monitor_fileaccess_v2.cpp spun forever on a queue overflow, because the overflow branch skipped FAN_EVENT_NEXT and re-tested the same event.
• 33 offline tests come with it, plain unittest so they also run on a worker node, and a CI job runs them.

Part of the o2dpg_workflow_runner.py refactoring.

[github-actions]

REQUEST FOR PRODUCTION RELEASES:
To request your PR to be included in production software, please add the corresponding labels called "async-" to your PR. Add the labels directly (if you have the permissions) or add a comment of the form (note that labels are separated by a ",")

+async-label <label1>, <label2>, !<label3> ...

This will add <label1> and <label2> and removes <label3>.

The following labels are available
async-2023-pbpb-apass4
async-2023-pp-apass4
async-2024-pp-apass1
async-2022-pp-apass7
async-2024-pp-cpass0
async-2024-PbPb-apass1
async-2024-ppRef-apass1
async-2024-PbPb-apass2
async-2023-PbPb-apass5