Change speaker color for those who are color anomaly

[bsclifton]

Carried over from brave/browser-laptop#1754

In browser-laptop, we (default on) have the option to show the tabs in theme color. This presents a problem when rendering the audio icon

For those who are color anomaly the combination of red and blue is uncomfortable, like this case on Youtube.

I propose to change blue into white, same as the title color.

Even if we don't implement tab theme color (captured with #905), we should consider making the speaker color high contrast enough to be easily seen