FIX Stop silently ignoring technique_converters

[Utkarsh Bahuguna (u7k4rs6)]

Fixes #3020.

• Doctor and AdversarialBenchmark now pass technique_converters to the matrix builder, so they apply them.
• Added Scenario.SUPPORTS_TECHNIQUE_CONVERTERS (default True). The scenarios that never applied them set it to False, so they don't declare the parameter and passing it raises the usual unknown-parameter error instead of being dropped. That's AdaptiveScenario (and TextAdaptive), AudioAchillesHeel, Encoding, PackageHallucination, Psychosocial, RedTeamAgent, Scam, SystemPromptExtraction and WebInjection.

Wiring the converters into those nine for real is doable but each builds its attacks differently, so I kept this to making the failure loud. Happy to do that as a follow-up for any of them.

Tests: one checking which scenarios declare the parameter, one that Encoding rejects it, one that Doctor appends the converter to the right technique, and one that the benchmark forwards it to the builder. 13 of them fail on main. tests/unit/scenario and tests/unit/backend: 3459 passed.