Add guild settings getter in command events

Pull Request

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• [x] I have checked the pull request page for upcoming or merged features/bug fixes.
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Pull Request Information

Check and fill in the blanks for all that apply:

• [ ] My PR fixes a bug, error, or other issue with the library's codebase.
• [x] My PR is for the command module of the JDA-Utilities library.
• [ ] My PR creates a new module for the JDA-Utilities library: ______.

Description

Describe your PR here. This PR adds 2 utility methods in the command and interaction events for getting the settings of the guild, using the class of the settings. Those methods will do the following checks:

• the command was run in a guild
• the settings manager is not null
• the settings manager does not return null settings
• the settings returned by the manager are instances of the specified settings class

How does this differ from event.getClient().getSettingsFor(event.getGuild())?

That method uses a generic argument which can't be inferred as it has no parameters using it. As such, it needs the type declared like .<Config>getSettingsFor(), which is annoying both to type and to look at. Plus, providing the wrong generic argument throws a class cast exception.

Can this be added to the Interactions class? Unless I'm missing something.