Update SK example, fix bugs

[jasongin]

• Update Semantic Kernel package in the example to 1.0.0-beta8, and revise JS code for API changes
• Skip indexed properties when marshalling structs. SK added a reference to System.Text.Json.JsonElement which is a struct with an indexed property that returns (another) JsonElement. This caused a stack overflow: Struct property with circular reference can cause stack-overflow in JS marshalling expression builder #181. Skipping indexed properties is correct anyway and is a convenient way to avoid the crash for now, though structs with non-indexed self-referential properties may still trigger it. (I have not found any yet.)
• Add limited support for marshalling ReadOnlyMemory<T>, only when the memory was originally allocated by a JS typed array. SK added some APIs that referenced ReadOnlyMemory<T> and that was causing an exception due to indirect references to Span<T> (which isn't supported and is normally skipped by the marshaller). Adding this special handling for ReadOnlyMemory<T> resolves the issue.
• Improve overload resolution for array parameters. SK loves to overload their APIs. (We don't yet handle resolution of overloads that differ only in object class: Marshalling: Advanced overload resolution #134)