feat: Add equals, hashCode, deep copy, and tests to OCICohereChatOptions

[apappascs]

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This commit enhances OCICohereChatOptions by:

• Updating equals and hashCode methods for proper object comparison.
• Updating copy() method, creating new instances of mutable collections (List, Set, Map, Metadata) to prevent shared state.
• Adding OCICohereChatOptionsTests to verify copy(), builders, setters, and default values.