Changes to the SlashCommandInteractionOptionsProvider

[felldo]

The SlashCommandInteractionOptionsProvider is an interface that contains methods to get options from a slash command interaction. Both the SlashCommandInteraction and SlashCommandInteractionOption interface implements it to be able to navigate through the options more conveniently.
Currently methods like getOptionLongValueByName only make sense if you are on the last "level" of the command. That means if the current option is a SUB_COMMAND or if the command has no sub command.
Therefore invoking these methods on the following command:
/base group subcommand <arg1>
they will always return an empty optional if you are currently on the base or group level.

To address this issue we should decide what should be done.
On the one side changing the behavior to get the options from SlashCommandInteraction#getArguments and renaming the methods would solve it but the API is not as fluent anymore if you are navigating though the options by yourself. Then if you are on the last level the getOptionLongValueByName methods would be missing. Then it might be a bit weird to call getArgumentLongValueByName although the options of the current option contains the arguments.
On the other side this change is not that bad because there shouldn't be any reason to get the arguments that way if you can call the convenience method getArguments or the new added methods.
Imo the advantages we get by doing this change is bigger than a bit less fluent API