Slash command support

[Chew]

THE CHUNKIEST PATCH IN EXISTENCE.

This adds support for Slash Commands. Phew!

Currently, this uses JDA's feature/slash-commands branch so this will be put on this repo's feature/slash-commands.

There's still a bit more to do, but it's pretty much done.

If you would like to test, you need to switch to my m2 repo:

        <repository>
            <id>chew-m2</id>
            <url>https://m2.chew.pro/snapshots/</url>
        </repository>

        <dependency>
            <groupId>pw.chew</groupId>
            <artifactId>jda-chewtils</artifactId>
            <version>1.20-SNAPSHOT</version>
            <scope>compile</scope>
            <type>pom</type>
        </dependency>

Check the wiki for migration guide.

[Andre601]

Suggested change

	private void onSlashCommand(SlashCommandEvent event)
	@Override
	private void onSlashCommand(SlashCommandEvent event)

[Chew]

The overrides only appear to apply when you extend ListenerAdapter, not EventListener that CommandClientImpl does 🤔 I can't exactly tell why or what benefits it has not doing it

[Chew]

Wrong button

[Chew]

Any final thoughts @Andre601 or is this good to go?

[Andre601]

Don't ask me