support arrays of color and colorscale for line and fillcolor of `plotly.graph_objects.Scatter`

Coming from plotly.py. Since this is about the plotly.graph_objects module, the issue is posted here.

Currently, only plotly.graph_objects.Scatter.marker, plotly.graph_objects.Scatter.marker.gradient and plotly.graph_objects.Scatter.marker.line supports assigning colors by arrays of color along with colorscale.

Could the same color-setting techniques be allowed for plotly.graph_objects.Scatter.line and plotly.graph_objects.Scatter.fillcolor as well?

p.s. Links to the current documentation:

1. The following supports arrays of color with colorscale:

• marker.color
• marker.gradient.color
• maker.line.color

2. The following doesn't support arrays of color with colorscale:

• line.color
• fillcolor

まず、Scatter.marker、marker.gradient、marker.line が colorscale とともにカラー配列を受け入れる仕組みを追跡し、次に Scatter.line と fillcolor の処理を比較します。既存のドキュメントリンクで期待される動作を確認し、スカラーの色を壊すことなく両方のプロパティで配列が機能することを示すカバレッジを追加します。