Add Figure.magnetic_rose to plot a magnetic rose on map

[seisman]

This PR implements the Figure.magnetic_rose method to plot a magnetic rose. It wraps the basemap/coast's -Tm option.

Preview:

The GMT CLI syntax is

-Tm[g|j|J|n|x]refpoint[+ddec[/dlabel]]][+ipen][+jjustify][+l[w,e,s,n]][+ppen][+tints][+odx[/dy]][+wwidth]

The Pythonic long-form parameters are:

• g|j|J|n|x: position_type
• refpoint: position
• +j: anchor
• +o: anchor_offset
• +w: width
• +p: outer_pen
• +i: inner_pen
• +l: labels
• +d: declination, declination_label
• +t: intervals

Examples

import pygmt
fig = pygmt.Figure()
fig.basemap(region=[-10, 10, -10, 10], projection="M15c", frame=True)
fig.magnetic_rose(
    position=(-5, -5),
    position_type="mapcoords",
    width="4c",
    labels=["W", "E", "S", "*"],
    intervals=(45, 15, 3, 60, 20, 4),
    outer_pen="1p,red",
    inner_pen="1p,blue",
    declination=11.5,
    declination_label="11.5°E",
)
fig.show()

Addressing #2831.