feat: Discord-style voice channel click-to-join with chat button

[ajlittle]

Summary

• Clicking a voice channel name in the sidebar now automatically joins the voice call and navigates to the channel (like Discord)
• Won't disconnect/reconnect if you click a channel you're already in
• Added a chat bubble hover action on voice channels to open the text chat without joining voice
• Keeps the existing header bar join button from PR feat: Mobile UI for web stoatchat/for-web#835

[Pecacheu]

Good idea, but this won't work on the mobile UI since hover action menus don't work with touchscreens. To solve that, you can add a matching action to ChannelContextMenu.tsx

Also side note, this creates a small merge conflict with my PR because I lifted the href out of the a tag and made it part of MenuButton (which was done in order to run some extra code in onClick so that clicking any channel/DM triggers an automatic swipe from channel view to message view.) Luckily the onClick listener can be applied to MenuButton instead because I have some code in there that calls the original onClick listener too if specified.

[ajlittle]

I wasn't really thinking from a mobile perspective on this. But from a UX perspective, having this current implementation on a touch device may lead to accidental joining of voice channels.

Probably best to be handled by a confirmation prompt that they would like to join the channel, like discord has. @Pecacheu