[BUG]: The `quiver` trace ignores a discrete `marker.color` array and results in every arrow being black

Description

The quiver trace ignores a discrete marker.color array. Every arrow ends up black instead of taking its per-point color. A numeric array with a colorscale works, and a single color string works.

Screenshots/Video

No colorscale (the bug)	With colorscale (for comparison)

Steps to reproduce

• Open plotly devtools
• Run the following snippet in the browser devtools console

   Plotly.newPlot(gd, [{
     type: 'quiver',
     x: [1, 2, 3], y: [1, 2, 3],
     u: [1, 1, 1], v: [0, 1, 0],
     marker: { color: ['rgb(23, 103, 194)', '#FF4136', '#2ECC40'], line: { width: 3 } }
   }]);
  

• Note that all three arrows are rgb(0, 0, 0) (by inspection of using your eyes)
• Run the following modified snippet:

   Plotly.newPlot(gd, [{
     type: 'quiver',
     x: [1, 2, 3], y: [1, 2, 3],
     u: [1, 1, 1], v: [0, 1, 0],
     marker: { color: [0, 5, 10], line: { width: 3 } },
     colorscale: 'Viridis'
   }]);
  

• Note that the arrows have the correct color

Notes

• marker.color is documented as arrayOk, so the black arrows seem to be a rendering bug (rather than an unsupported input)
• Per the schema, each arrow should be drawn as its own color from the array. If this behavior is intentional, we should update the description.
• This was found while working on #8025

Riproduci il problema tramite le chiamate a Plotly.newPlot negli strumenti per sviluppatori del browser, iniziando dall’implementazione della trace quiver. Confronta la gestione dell’array discreto marker.color con il caso di una colorscale numerica, quindi verifica che ogni freccia utilizzi il colore corrispondente, mentre i colori singoli e le colorscales continuino a funzionare.