[feature request] add option to replace "new tab" button with a new or blank tab

[this-username-system-sucks-ass]

I use zen with the replace.urlbar option in about:config turned off because I like having a new tab with a homepage. When set up like this what I end up with is, from top to bottom, essentials, pinned tabs, normal tabs, a new tab automatically created on startup, and the new tab button. The default way for zen to work is more along the lines of "on startup you can just start typing to search", but what I am seeing is "a new tab is made on startup".

I think if the new tab button was instead just an ever-present new tab (with a new one appearing below it whenever it is no longer a new tab) it would make the experience with the setting I mentioned earlier closer to the intended experience. given how often people ask about that setting in the discord I think this would improve things for enough users to be worth it. It would also improve the appearance because it is a little weird looking to have a tab that says "new tab" and a button that says "new tab" right next to each other (especially since an icon is the only visual difference between them).

I'm not sure how this would mesh with the default configuration (might be best to only have it happen when the setting I mentioned is off) but I think it's worth looking at and it would definitely improve my experience with the browser given the way I use it.