AudioDecoder.configure should not throw for invalid config

Per spec https://w3c.github.io/webcodecs/#dom-audiodecoder-configure

"If config is not a valid AudioDecoderConfig, throw a TypeError."

I think this is ambiguous, and there's even inconsistency in the tests where in one place we check that the config isn't valid and in the other that the same config is also not supported (I lodged
https://github.com/web-platform-tests/wpt/issues/49636 for this one)

Rather than throwing when a configuration isn't valid, we should just mark it as not supported; particularly when there's a lot of discrepancies already in what is considered a "valid" configuration (WPT checks that bitrate isn't 0, or too big, that the Opus description is greater than 9 bytes etc) which aren't in the spec and doesn't have broad acceptance across UAs

Start at the AudioDecoder.configure behavior described in the WebCodecs specification and compare the validity and support checks in the relevant Web Platform Tests. Resolve whether invalid configurations should be treated as unsupported rather than throwing, then update the implementation and tests so the chosen behavior is consistent with the specification and WPT expectations.