Houdini: Move Houdini Save Current File to beginning of ExtractorOrder

[BigRoy]

Brief description

In the spirit of this PR #2744 with this commit moving the order for the Save Scene plug-ins to beginning of ExtractorOrder this makes Houdini align with that too.

As discussed in the comments this seemed like the more sensible moment to save the current workfile.

Additional note

In Houdini there seemed to be two plug-ins involved with saving - one operating at a different target for different families.
We could technically add both in a single file and do something like:

class SaveCurrentScene(pyblish.api.ContextPlugin):
    """Save current scene"""

    label = "Save current file"
    order = pyblish.api.ExtractorOrder - 0.49
    hosts = ["houdini"]
    targets = ["deadline"]

    def process(self, context):
        ...

# Inherit from SaveCurrentScene to always save for all families for target `deadline`
class SaveCurrentSceneDeadline(SaveCurrentScene):
    hosts = ["houdini"]
    targets = ["deadline"]

That way the logic could be less duplicated and the Save plug-ins close together.

[antirotor]

Shouldn't we add more families there, or maybe use it for all of them?

[BigRoy]

Shouldn't we add more families there, or maybe use it for all of them?

Quickly checked with our Houdini artist - he had no issue with scene being saved on all families by default. We can always tone that down if we notice issues with that approach.

[BigRoy]

or maybe use it for all of them?

Implemented with 7de42ee