feat(ios)!: Improve AudioContextIOS

[Gustl22]

Description

• Add assertions for AudioContextIOS
• Convert AudioContextIOS.options from List to Set

Closes #1584

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, refactor:,
  docs:, chore:, test:, ci: etc).
• I have read the Contributor Guide and followed the process outlined for submitting PRs.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation and added dartdoc comments with ///, where necessary.
• I have updated/added relevant examples in example.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

Migration instructions

Before:

const AudioContext();
const AudioContextIOS();
AudioContextIOS(options: [ /* ... */ ]);

After:

AudioContext();
AudioContextIOS();
AudioContextIOS(options: { /* ... */ });

Related Issues

Closes #1584