feat: Rework CLI introspections

[LukeMathWalker]

--debug was a very overloaded CLI flag: it rendered the full diagnostic error chain, exported perf profiling info and enabled internal logging. In most cases, that's undesirable:

• Users will often reach for the full diagnostic error chain
• Maintainers, instead, will look for perf profiles and internal logging

To better accommodate these usage patterns, --debug will now be limited to diagnostic error chains. We introduce --perf-profile to emit trace files, --log for internal logging and an explicit --log-filter to configure what gets logged.

[LukeMathWalker]

/ok-to-test sha=492bc26