[feature] Option to disable status icon

[lofidevops]

User story: I am an everyday GNOME user, I am used to apps that follow the GNOME HIG. When I start an application I do not want a legacy status icon, as this is redundant and confusing.

Suggested solution: In Revolt Preferences dialog, add a "Use status icon" checkbox. If checked (default), the status icon appears. If unchecked, the status icon does not appear. Notifications work as normal either way.

(I suggest the option be checked by default as it seems that a status icon is the expectation of the majority of users, including GNOME power users who are patiently waiting for better notifications in GNOME as described in #41 )

Notes:

• This is an attempt to make a concrete suggestion to address the GNOME HIG issue discussed in #41 without compromising UX for other users.