Swap to Tab Group dropdown menu and improve compatibility with stacked tabs

[Gorkycreator]

Thanks for making this nifty plugin! I came across it yesterday and really like it. There were a few things I discovered while making my own plugin that I thought might add some polish, so I made a fork for my own use. If you like the ideas, please feel free to incorporate them.

This PR does two things:

1. Remove the menu item from the right-click context menu and place it instead in the tab group dropdown, like so:
   
2. Manage Obsidian's state so that Continuous Mode and Stacked Tabs are never simultaneously enabled, since they compete for modifying the tab layout.

The state management works by replacing native Obsidian callbacks, which is slightly hacky. I've done my best to add safety checks and minimize breaking updated Obsidian behavior, but there may be a better way to implement this.

[gasparschott]

Glad you like the plugin.

I've added the continuous mode menu item to tab-group menu; thanks for the suggestion. I've kept the menu item name the same for now, with the checkmark added when it is active, but I might change it later.

As for the issue with Stacked tabs, I had looked into this when I was developing the plugin. The CSS does disable some styles when stacked tabs are activated, but I thought the arrow navigation function was useful in stacked tabs mode. What particular conflicts do you see?

Thanks.

[Gorkycreator]

Using the arrow keys in stacked mode is pretty useful, I just didn't know you could do that!

There weren't any technical issues in stacked mode, it just seemed a bit unintuitive as a new user. If you're already in stacked mode and enable continuous mode, it looks like the plug-in just isn't working... It might be good to add some documentation so users know it's an intended feature.

Thanks again for the nifty plug-in! I've been really enjoying having a stack of motivational/planning notes next to my main workspace 😁