Feature request for colorbar support on geographic axes

[lwq-star]

Hello,

I am using the Ultraplot library to create a 2×2 grid of subplots. The first row consists of geographic axes, while the second row contains regular (non-geographic) axes.

I created a colorbar for the geographic plots, but I would like to position the colorbar between the two rows of subplots, spanning across both columns.

However, in my attempts, the colorbar always appears below the first subplot instead of being centered between the two rows.

How can I correctly place the colorbar in the middle between the two rows and have it span across the columns?

This issue is similar to #392.

import ultraplot as uplt
import numpy as np

fig, axs = uplt.subplots(nrows=2, ncols=2, proj=["npstere", "npstere", None, None])

rng = np.random.default_rng()
data = rng.random((100, 100))

cm = axs[0, 0].pcolormesh(data)
fig.colorbar(cm, loc="b", ax=axs[0, :], span=(1, 2))