Send message

# Polymorphic send
this is going to involve a lot of overload signatures and type checking.

`Group#send(text: string): Promise`
`Group#send(options: GroupSendMessageOptions): Promise`

Sends a message to a group.

Usage:
```js
const group = client.groups.cache.get('12345')

group.send('hi guys')
group.send({
text: "here's a picture of my dog",
image: "https://i.imgur.com/NPUoRh5.png"
})
```

come up with more overloads later, like sending a message with only an image or a user resolvable or something like that