AVContentKeySpecifier options are not typed

Xcode 12.5 introduced AVFoundation updates - the options mentioned in the new `AVContentKeySpecifier`methods (below) are not specified and the documentation is unclear.

As a result, these options are not typed, but a strong dictionary would improve code context

```cs
/*!
@method contentKeySpecifierForKeySystem:identifier:options:
@abstract Creates a new instance of AVContentKeySpecifier.
@param keySystem
A valid key system for content keys.
@param contentKeyIdentifier
Container and protocol-specific key identifier.
@param options
Additional information necessary to obtain the key, can be empty if none needed.
@result A new AVContentKeySpecifier
@discussion This method returns an AVContentKeySpecifier instance that represents a content key in a specific content key system.
*/
+ (instancetype)contentKeySpecifierForKeySystem:(AVContentKeySystem)keySystem identifier:(id)contentKeyIdentifier options:(NSDictionary *)options;

/*!
@method initForKeySystem:identifier:options:
@abstract Initialize an instance of AVContentKeySpecifier.
@param keySystem
A valid key system for content keys.
@param contentKeyIdentifier
Container and protocol-specific key identifier.
@param options
Additional information necessary to obtain the key, can be empty if none needed.
@result An instance of AVContentKeySpecifier
@discussion This method returns an AVContentKeySpecifier instance that represents a content key in a specific content key system.
*/
- (instancetype)initForKeySystem:(AVContentKeySystem)keySystem identifier:(id)contentKeyIdentifier options:(NSDictionary *)options;
```