Abstract KV layer options to eliminate dynamic casts to FDBTransaction

[Clcanny]

The use of dynamic_cast can bypass the common functionality defined by the interface classes (IReadOnlyTransaction and IReadWriteTransaction) and instead rely on specific implementation details. This might not be ideal, as it reduces abstraction and increases coupling to a particular implementation. To address this, I attempted to define common option-setting functions.

I considered two approaches:

1. Providing a universal function such as setOption(TransactionOption option, std::string_view value) that can handle all options.
2. Using separate, specific functions like enableStaleRead and setPriority.

I chose the second approach because it assumes there are not many options to set, and this method is clearer and type-safe compared to passing raw value strings.

Thank you for taking the time to review. Feel free to close the MR if it is too small or not helpful.