Set AyonUsdResolver as the preferred resolver for Maya

[tadeas-hejnic]

Changelog Description

This PR adds a prelaunch hook that is responsible for setting the AyonUsdResolver as the preferred one. This functionality can be enabled/disabled in settings.

The reason of this is to avoid issues with loading only the default Autodesk resolver, which is technically disabling the AYON one.

Testing notes:

1. launch Maya with usd addon, test if the resolver was loaded and run this code from the issue:

from pxr import Ar
import time
from usdAssetResolver import AyonUsdResolver

Ar.SetPreferredResolver("AyonUsdResolver")
resolver = Ar.GetResolver()
context = AyonUsdResolver.ResolverContext()

2. launch app without defined resolver path in settings -> see the logs

[BigRoy]

Some small remarks. After that, can you update the testing notes to include some small Python snippet for Maya so we know what to test for.

Then let's see if @MustafaJafar can review.

[Copilot]

Pull request overview

This PR aims to ensure Maya prefers the AyonUsdResolver (instead of falling back to Autodesk’s default resolver) by injecting an AYON USD Maya startup script via a pre-launch hook, and setting Ar.SetPreferredResolver("AyonUsdResolver") during Maya startup.

Changes:

• Add a Maya userSetup.py startup script that sets AyonUsdResolver as the preferred USD resolver.
• Add a Maya-specific pre-launch hook to add the startup directory to PYTHONPATH.
• Add explicit hook ordering and a shared ayon_usd_resolver_initialized flag to coordinate hook execution.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
client/ayon_usd/startup/maya/userSetup.py	Adds a Maya startup entry point that sets the preferred USD resolver.
client/ayon_usd/hooks/pre_resolver_init.py	Adds hook order and a shared data flag to indicate resolver init success.
client/ayon_usd/hooks/pre_maya_launch.py	Adds a Maya pre-launch hook that injects the startup script location into PYTHONPATH.

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[BigRoy]

LGTM. @MustafaJafar can you review? @antirotor if you have time, can you give your thoughts on approach?