Add `--task-config <blob>`?

[jcjones]

Yeah... TaskConfiguration is task-shape only; the collector still needs the things that aren't in it: task_id, collector auth token, collector HPKE keypair/credential, and the query itself (batch interval / leader-selected).

So the shape would be, like: "one --task-config <blob> replaces the DAP-task-parameter flags, existing credential/query flags stay."

collect.rs is the natural first consumer. I'll make note of this to think through, too!

Originally posted by @jcjones in #4698 (comment)

[jcjones]

Whatever we do here should also adjust the interop_binaries/src/commands/janus_interop_collector.rs too.