improv: filter firefox player

[wiiznokes]

when using the plasma extension on firefox, player will be duplicated. The org.mpris.MediaPlayer2.plasma-browser-integration gives better results

[mpris2/src/media_player.rs:40:3] &players = [
    OwnedBusName::WellKnown(
        "org.mpris.MediaPlayer2.firefox.instance_1_379",
    ),
    OwnedBusName::WellKnown(
        "org.mpris.MediaPlayer2.plasma-browser-integration",
    ),
]
Mozilla org.mozilla.firefox (org.mozilla.firefox)
        Playback Status: Playing
        Position: N/A
        Doesn't support seeking
        Supported Rates: N/A
        Current Rate: N/A
        Metadata: {xesam:artist: [""], xesam:title: "(30) Mac Miller - Self Care - YouTube", mpris:trackid: "/org/mpris/MediaPlayer2/firefox", xesam:album: ""}
        Tracks: N/A
        Playlists: N/A
[mpris2/examples/list.rs:18:3] media_player.inner().destination() = BusName::WellKnown(
    "org.mpris.MediaPlayer2.plasma-browser-integration",
)
Mozilla Firefox (firefox)
        Playback Status: Playing
        Position: 1.5466449 seconds
        Supports seeking
        Supported Rates: 0.01x through 32x
        Current Rate: 1x
        Metadata: {mpris:trackid: "/org/kde/plasma/browser_integration/1337", mpris:artUrl: "https://i.ytimg.com/vi/SsKT0s5J8ko/hqdefault.jpg?sqp=-oaymwEcCNACELwBSFXyq4qpAw4IARUAAIhCGAFwAcABBg==&rs=AOn4CLAbW4yvMJwrL_naXuEPiHOIDtBuwA", xesam:artist: ["Mac Miller"], kde:pid: 340574, mpris:length: 347221000, xesam:url: "https://www.youtube.com/watch?v=SsKT0s5J8ko", xesam:title: "Mac Miller - Self Care"}
        Tracks: N/A
        Playlists: N/A

With this fix, the applet will show

Mac Miller - Self Care
Mac Miller

instead of

(30) Mac Miller - Self Care - YouTube

With youtube music,

Self Care
Mac Miller

instead of

Youtube music

when inactice, or

Self Care - Youtube music

when active

[mmstick]

Thanks!