Make singers and translation into individual layer.

[andy840119]

Like the connection points between hitCircle in osu ruleset.
see the FollowPointRenderer and the FollowPointConnection.

The main benefit is let the lyric focus on showing the karaoke text.
And will be easier to show/hide those properties.

[andy840119]

Note that translation or singer might not follow the position in the lyric in every stage.
e.g: translation might be at the bottom if current stage is preview stage.

[andy840119]

maybe see how FollowPointRenderer works?

Also, we should make the base renderer for able to renderer the property for the lyric.