Light/dark map tile variants

[Terrance]

Is your feature request related to a problem? Please describe.

Metabase does not offer a dark/night theme (see #9203), though browser extensions like Dark Reader work well enough to customise the styles for a dark mode. Where this falls short is with map tiles, which remain unchanged and are rather blinding alongside the rest of the site in a dark theme.

Describe the solution you'd like

If and when a site-wide dark mode is available, the option to configure light and dark tiles independently, and for them to be used with the corresponding theme. Ideally, a default dark tile set would be available as with the current light tiles, though I don't know if OSM provides their own for this or if a third-party tile provider would be needed.

Describe alternatives you've considered

I could just equip a dark tile set all the time, though I find them less legible during the day, and a dark map against an otherwise white website also looks a bit jarring.

Switching between light and dark map tiles manually is also a bit painful as there's nowhere to "store" the dark tile URL when not in use (i.e. I'd need to dig it out from somewhere else and paste into the settings field each time).

How important is this feature to you?

A fair few of my regular visualisations are map-based, and I refer to them at various hours of the day, so I do frequently notice this.

Additional context

Here's how it looks currently (default map tiles with Dark Reader's "dynamic" theme):

And using e.g. Dark Matter tiles (https://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png):