Context Menu for snapping view to primary axis planes in 3D plots

[AdwaithBatchu]

PR summary

closes 23544
This PR introduces a feature that adds context menu on 3d Axes triggered by right-click of the mouse.

1. Added context_menu() in Figure Manager that takes arguments, a list of labels and a list of corresponding functions to execute upon selection.

2. Modified _button_release() to call canvas.manager.context_menu() with functions for setting orthographic views when the right-click is released on the mouse without moving it significantly. Mouse movement is handled in _on_move() using a small threshold because previously I observed trackpad (on macOS) reported micro-movements during a static click, which falsely flagged the action as "drag" and blocked the menu in specific backends.

Backends

• TkAgg: tk.Menu implementation.
• QtAgg: QtWidgets.QMenu implementation.
• WxAgg: Uses wx.Menu and PopupMenu.
• Gtk3Agg: Uses Gtk.Menu.
• Gtk4Agg: Uses Gtk.PopoverMenu and Gio.Menu.
• MacOSX: Uses AppKit (PyObjC) to display a native NSMenu, utilizing a target/action dispatcher.
• WebAgg: Yet to be implemented
• NbAgg: Yet to be implemented

import matplotlib

# matplotlib.use("TkAgg") # Change to QtAgg, GTK4Agg, MacOSX, WxAgg, etc.
import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(projection="3d")
ax.plot([0, 1, 2], [0, 1, 0], [0, 1, 0])

plt.show()

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• Plotting related features are demonstrated in an example
• New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines

[r3kste]

@AdwaithBatchu The backend implementation is slightly wrong right now. As discussed previously:

• There should be no mention of 3d axes or view_init within the backend files. After all these files should be as general as possible.
• You only need to add a function named context_menu in the FigureManager class.

[r3kste]

@AdwaithBatchu I have some concerns about implementation in Gtk4 and MacOSX.

Apart from that, I want you to link to the official documentation of the context_menu for each backend. For example, I have added a comment for qt backend. Do this for the other implemented backends.

[r3kste]

@AdwaithBatchu

[r3kste]

@AdwaithBatchu This is pretty close. The main thing is that

Make sure all backends use a consistent method for determining location
1. Current mouse position
2. Extract coords from event

Both will (should) give the exact same output, but for sake of consistency we should use a single method. I think (ii) is better, but let me know if you think otherwise

[r3kste]

@AdwaithBatchu