port nowplaying window

[mikelxk]

@Dumeng I tried to port your change in now playing window from #755 but there's this weird gap.

Do you have time to take a quick look?

[listen1]

make some modifications for now playing style

• change now playing show animation time to 300ms, 500ms seems a little slow
• move music cover closer to lryic column
• fix lyric last line hide because placeholder height too small bug
• change lyric placeholder height from 1/2 height to 1/3 height, because it seems too empty when song begins
• smaller margin top of comment zone