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

先追蹤 Scatter.marker、marker.gradient 和 marker.line 如何接受搭配 colorscale 的色彩陣列，然後比較 Scatter.line 和 fillcolor 的處理方式。在現有文件連結中確認預期行為，並新增覆蓋測試，展示陣列對這兩個屬性都有效，同時不會破壞純量色彩。