Check stub tasks against their task handlers

[jason810496]

Stack (bottom to top), on native #74037 (stack #74170): #73973, #73974, #73975, #74317, #73976, #74067, #74135, #74140, #74141, #73971, #74030, #74031, #74032, #74136, #74137, #74138, #74139

Adds the checks that compare a Dag's stub tasks with the task handlers a probe reports, so a missing handler or an argument a handler cannot take fails the Dag file's import instead of the task on a worker. They are pure functions, and nothing calls them yet: #74135 does.

stub_tasks = collect_stub_tasks(bag.dags.values(), serialized_dags)
etl_go = [stub for stub in stub_tasks if stub.dag_id == "etl" and stub.queue == "go"]
answer = TaskHandlerAnswer(
    bundle_name="go-task-handlers",
    rel_path="bin/etl",
    task_handlers=result.task_handlers,  # the TaskHandlerParsingResult of the probe
)
match = match_task_handlers(etl_go, answer)  # one Dag's stub tasks that route to one coordinator
match.warnings  # name mismatches under named binding, for the parse log
format_import_errors(match.problems)
# {"dags/etl.py": "Stub tasks in dags/etl.py do not match their task handlers:\n"
#                 "- Dag 'etl', task 'load': 'bin/etl' in Dag bundle 'go-task-handlers' registers no task handler for it\n"
#                 "- Dag 'etl', task 'transform' ('bin/etl' in Dag bundle 'go-task-handlers'): "
#                 "argument 'count' is integer or null, the task handler takes integer"}

• A stub task with no handler is a problem, but a handler with no stub task is not, because one artifact registers handlers for many Dag files. ADR-0011 used to require the ids to match exactly.
• Arguments are checked the way the runtimes bind them:

Declaration	Import error	Parse-log warning
positional	An argument count that matches the params neither with nor without the defaulted arguments, or a value type the param at that position does not accept	none
named	A value type the matched param does not accept	An argument no param takes, or a param no argument fills, unless a lone argument may be the whole value
params=None, or a mapped stub task	none, only the handler's presence	none

• Under named, a param takes the argument of its exact name, else, unless exact_name is set, the one whose name folds to its own (lower case, _ removed). A folded name two arguments share matches neither.
• Types are compared only where both sides have a schema, as the Go runtime compares them: an argument that may be null needs a param that accepts null, and at least one of its other types must be accepted, with integer accepted by number. So int | str binds to an integer param and int | None does not. $ref, format, ranges and nested items are not compared.
• Arguments are read from the serialized Dag as JSON, so they are what the worker gets: a tuple becomes a list, and a dict key a string.
• ADR-0011 (Step 5, Consequences and Appendix B) states these rules, and ADR-0012 and ADR-0013 point to it.

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