frontend: TopBar: Hide menu on mobile when empty

[skoeva]

This change hides the top bar menu on mobile when there are no actions to display.

Fixes: #2066

Testing

• Open Headlamp in the mobile view
• Ensure that the top bar menu shows up only when there are available actions

[sniok]

Thanks for taking a look at it

I tried it and the menu was always missing, I left a comment on the place that has an issue.

Also I think this PR is a good place to also fix the look of the menu on mobile
It's a bit awkward with just an icon in the middle, I think adding label to buttons and aligning them to the left would look a lot better. Similar to how other popup menus look in the app

[skoeva]

Tested by enabling/disabling the dynamic-clusters plugin, and works as expected:

• When the plugin is enabled, the menu shows up with the dynamic cluster button

• When the plugin is disabled, the menu does not show up

[joaquimrocha]

I am a bit puzzled with this one, since it looks like we are changing the functionality that plugins may be overriding. @sniok can you check/confirm this?
It at least looks like we should have a couple of commits, since the original issue is a menu that is rendering as empty.

[sniok]

I am a bit puzzled with this one, since it looks like we are changing the functionality that plugins may be overriding

Yeah so my request was to change how the buttons look on mobile (icon with a label).
And now it does that and looks a lot better but at the same time breaking compatibility with plugins by introducing a new separate properties to AppBarAction.
And we can't really do that, we need to keep rendering only .action component.

I think a better solution here is to render different buttons depending on which menu it is (desktop/mobile), that way we don't have to introduce any new fields or break compatibility

const allAppBarActions = [
   { action: <SettingsButton />, }
   // ...
];

const mobileAppBarActions = [
  { action: <SettingsButton variant="mobile" /> }
  // ...
]

But looking at how the scope of this PR keeps growing how about we limit this PR to the initial fix (not rendering menu when it's empty). And then any additional improvements we can move into a new PR. @skoeva What do you think?

[skoeva]

@sniok Sounds good. Will move the additional changes into a new PR and adjust this one accordingly