Fix support for open last workfile with AVALON_SCENEDIR

[BigRoy]

Changelog Description

Fix support for open last workfile with AVALON_SCENEDIR + cosmetics

Additional info

Resolves #5126

Testing notes:

1. Enable launch last workfile (= enabled by default)
2. Add "AVALON_SCENEDIR": "scenes" to e.g. the houdini or maya environment
3. Save a workfile with the Workfiles tool.
4. Restart the application, it should launch the existing workfile directly.

[iLLiCiTiT]

Like I've mentioned in discord communication. We didn't want to support scenedir, only for host integrations that require it. In that case it is handled by the host addon. That discussion happend few months ago, so maybe we can reopen the discussion @antirotor @mkolar @jakubjezek001 . But with that in mind, I don't know if this will be approved.

[BigRoy]

Link to the 'discord communication'

Thanks - just for context: we've been using AVALON_SCENEDIR all the time for Houdini, Fusion and Maya. So being able to have a subfolder for our workfiles for those applications will be a requirement for us for backwards compatibility and also a forward preference to still allow that behavior as it's preferred by our artists too.

As described in #5126 I'm fine with dropping AVALON_SCENEDIR if there's a replacement built-in feature through which we can define the workfiles subdirectory in the work root per application.

We also have our workdir template include the {app_name} so we have e.g. work/{task}/{app}/{scenedir} resulting in work/animation/maya/scenes. The maya workspace.mel still resides in the work root (maya/ folder) but the workfiles themselves end up in scenes subfolder. This is the behavior we're looking to preserve (and with this PR also support at least with last workfile open on launch)

[BigRoy]

We are currently using this in production 👍

[mkolar]

I agree with the functionality, but I think we need a slightly different approach. We have some requests to make the workfile handling a little more robust, and this should be included in there. We'll prep some proposal soon hopefully.

[mkolar]

Because we're splitting OpenPype into ayon-core and individual host addons, this PR would have to be re-created to target one of those. The PR has merit, the solution, not so much. Let's try to revisit in AYON

We're closing it down, but we'll he happy for a new PR to ynput/ayon-core repository once it's up.