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

首先追踪 Scatter.marker、marker.gradient 和 marker.line 如何接受带有 colorscale 的颜色数组，然后比较 Scatter.line 和 fillcolor 的处理方式。在现有文档链接中确认预期行为，并添加覆盖测试，展示数组对这两个属性都有效，同时不会破坏标量颜色。