SG-38779 Context ready to be used after open file from scene hook

[eduardoChaucaGallegos]

This pull request enhances the Houdini engine's support for dynamic context switching without requiring a restart. It introduces mechanisms to update the UI (menu and shelf) when the context changes, ensuring that the interface accurately reflects the current context and available commands.

Context switching and UI update improvements:

• Added the context_change_allowed property to the HoudiniEngine class, enabling the engine to support context changes without a restart.
• Implemented the post_context_change method in HoudiniEngine to update the menu and shelf UI elements after a context switch, ensuring they display commands relevant to the new context.

UI refresh functionality:

• Added a refresh method to both the menu and shelf classes in tk_houdini/ui_generation.py, allowing them to invalidate cached data and update their command lists when the context changes.

Test

[carlos-villavicencio-adsk]

LGTM