Fix release-build panic in resolve_color_choice

[popematt]

Issue #, if available:

None

Description of changes:

When testing Ion CLI before publishing the 0.12.0 release, I discovered a bug. It turns out that a function I had been using as a guard to prevent panics is actually a no-op when you do a release build, so all my previous testing had missed it.

Clap's try_contains_id relies on verify_arg which is gated behind #[cfg(debug_assertions)], so it always returns Ok(()) in release builds. Commands that don't register --color/--no-color (e.g., inspect) would pass the guard, then get_flag("color") would panic because the arg was never configured with ArgAction::SetTrue.

The fix uses try_get_one::<bool> with pattern matching. For SetTrue args, clap stores a default value, so Ok(Some(&false)) means "registered but not passed" while Ok(None) (release) or Err (debug) means "never registered." The wildcard arm returns ColorChoice::Never, preserving the original semantics.

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