Implement macos AppDelegate

[greglucas]

PR summary

This suppresses a warning that appears with MacOS 14+. WARNING: Secure coding is not enabled for restorable state!

Thanks, @QuLogic and @tacaswell for the pointers on what needed to be done!

Testing: It seems like Python compiled with clang 15+ doesn't produce this warning, but installing Python 3.12 downloaded from python.org uses clang 13 and I do get the warnings locally.
Running a simple script you should see the warnings on main and then they should go away on this branch.

import matplotlib.pyplot as plt
plt.plot([1, 2, 3])
plt.show()

closes #27389

PR checklist

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

[QuLogic]

Seems to make sense from a code point of view. Maybe @dstansby could test it?

[tacaswell]

Merging on strength of: #27389 (comment)

[tacaswell]

Thanks @greglucas !