Application buttons - Allow adding & hiding buttons locally

[ThomasK33]

Template authors might add multiple IDEs and editors to cater to a broader group. However, as an individual developer, I might only be interested in VS Code, not JetBrains IDEs. Thus, one can show and hide icons based on personal, locally stored preferences. These can be preferences stored in "global" settings, like the HTTP headers, or on a per workspace level.