fix: equation to model and default configurations

[blanchco]

Description

Fixes for equations to amr:

• when saving equations to amr, the editing state will close.

Fixes for default config:
Before:

• when creating a model and there were no default configurations, an empty default config would be made and never updated.
• specifically when called equations_to_amr, the knowledge-middleware would create a model configuration that was no the 'Default config', we then ended up with an empty 'Default Config' and a new model configuration from knowledge-middleware.

After:

• an empty model config will not be made automatically when a new model is create (there is an empty check for states and transitions)
• when the model is updated and there are no configurations a default config will be created if it does no already exist.

This PR will need a follow-up PR for it to fully be completed. In the knowledge-middleware the model configuration through equations_to_amr will need to be called 'Default config'.

Screen.Recording.2023-10-11.at.4.48.28.PM.mov