[Bug Report] No handling for no internet connection

Nobody has claimed this yet.

### Bug Description

When running the bot without an internet connection, the JDA connection attempt will fail without catching the exception and doing a proper system exit. When a server (physical PC) running the bot restarts, if there is no internet connection when the system starts, the bot will fail without crashing and therefore cannot be restarted automatically.

`[06:02:09] [ERROR] [Requester]: DNS resolution failed: discord.com: Name or service not known
Exception in thread "main" net.dv8tion.jda.api.exceptions.ErrorResponseException: -1: java.net.UnknownHostException
at net.dv8tion.jda.internal.requests.RestActionImpl.complete(RestActionImpl.java:227)
at net.dv8tion.jda.api.requests.RestAction.complete(RestAction.java:633)
at net.dv8tion.jda.api.utils.SessionControllerAdapter.getGateway(SessionControllerAdapter.java:86)
at net.dv8tion.jda.internal.JDAImpl.getGateway(JDAImpl.java:318)
at net.dv8tion.jda.internal.JDAImpl.login(JDAImpl.java:276)
at net.dv8tion.jda.internal.JDAImpl.login(JDAImpl.java:268)
at net.dv8tion.jda.api.JDABuilder.build(JDABuilder.java:1874)
at com.jagrosh.jmusicbot.JMusicBot.startBot(JMusicBot.java:187)
at com.jagrosh.jmusicbot.JMusicBot.main(JMusicBot.java:65)
Caused by: java.net.UnknownHostException: discord.com: Name or service not known

...

Caused by: net.dv8tion.jda.api.exceptions.ContextException
at net.dv8tion.jda.api.exceptions.ContextException.here(ContextException.java:54)
at net.dv8tion.jda.api.requests.Request.(Request.java:71)
at net.dv8tion.jda.api.requests.RestFuture.(RestFuture.java:36)
at net.dv8tion.jda.internal.requests.RestActionImpl.submit(RestActionImpl.java:209)
at net.dv8tion.jda.internal.requests.RestActionImpl.complete(RestActionImpl.java:219)
at net.dv8tion.jda.api.requests.RestAction.complete(RestAction.java:633)
at net.dv8tion.jda.api.utils.SessionControllerAdapter.getGateway(SessionControllerAdapter.java:86)
at net.dv8tion.jda.internal.JDAImpl.getGateway(JDAImpl.java:318)
at net.dv8tion.jda.internal.JDAImpl.login(JDAImpl.java:276)
at net.dv8tion.jda.internal.JDAImpl.login(JDAImpl.java:268)
at net.dv8tion.jda.api.JDABuilder.build(JDABuilder.java:1874)
at com.jagrosh.jmusicbot.JMusicBot.startBot(JMusicBot.java:187)
at com.jagrosh.jmusicbot.JMusicBot.main(JMusicBot.java:65)`

### Steps to Reproduce

1. Start the bot without an internet connection

### Expected Result

I expect the bot to system exit if launched with no internet connection

### Debug Output

OS: Debian GNU/Linux 11 (bullseye)
JMusicBot: 0.3.8

### Additional Info

_No response_

### Checklist

- [X] I have looked for information about this [within the documentation](https://jmusicbot.com/)
- [X] I have searched for similar issues [on the issues page](https://github.com/jagrosh/MusicBot/issues?q=is%3Aissue)
- [X] I am running the latest version of the bot: 

Start in JMusicBot.java at the startBot and main entry points shown in the stack trace, and trace the connection attempt made during startup. Reproduce the launch without an internet connection and verify that the bot exits with the expected failure behavior so an automatic restart can occur.

Written by the indexing model from the issue text.