feat: add tab overflow menu (#1592)

[Tamriel]

closes #1592

[trusz]

Thank you for your contribution!

The solution looks nice and I would like to ask for a few changes to finalize the solution. You can of course let us know if we should take over from here.

1. I have small code change request about adding and removing event listeners.
2. Also, I was wondering if you could place the overflow menu at the and of the row and not at the beginning. I think they are usually there.
3. The style of the selected tabs have changed a bit. Would it be possible to revert them how they've looked like?
4. I think it would be nice somehow to display the currently active plugin even if it in the overflow menu, but currently I do not have an idea how. I am open to suggestions.

[trusz]

I think this won't remove the original one.
I would recommend creating a function that we can reference.
something along these lines:

private calculateVisibleTabs = () => {
...
}

By using an arrow function we make sure that we have the correct context (this) without binding the function.
With that you can add and remove listeners:

window.addEventListener('resize', this.calculateVisibleTabs)
window.RemoveEventListener('resize', this.calculateVisibleTabs)

[Tamriel]

1. Thanks for the hint that removing the resize listener did not work. I fixed it now.
2. The overflow menu is now placed at the end of the row - I like this solution better as well.
3. I find styling Material Web Components quite painful, because there are many fixed/internal styles. I've adjusted the buttons to look more like mwc-tab-bar, but I couldn’t increase the icon size or vertical padding. Any ideas?
4. My idea for improving the UI: If the active plugin is hidden in the overflow menu, move its button to the right-most visible position, and move the button currently there into the menu instead. This could be repeated if needed (e.g. if the active button is wider).