Make STEMMUS_SCOPE BMI-able

[BSchilperoort]

Description

This PR will make STEMMUS_SCOPE compatible with a full BMI implemented in Python.

The documentation on this is still to-do (once PyStemmusScope has the BMI implemented https://github.com/EcoExtreML/STEMMUS_SCOPE_Processing/pull/89)

Checklist

• [x] Add a reference to related issues.
• [x] @mentions of the person or team responsible for reviewing proposed changes.
• [x] This pull request has a descriptive title.
• [x] Code is written according to the guidelines.
• [x] The checks by MISS_HIT style checker and linter, below the pull request, are successful (green).
• [x] Documentation is available.
• [x] Add changes to the changelog file under section Unreleased.
• [x] Model runs successfully.
• [x] Ask a maintainer to re-generate exe file if matlab codes are changed. About how to create an exe file, see exe readme.

[BSchilperoort]

@SarahAlidoost first local test of running the model's initialization, update and finalize steps separately seems to be successful! Thanks for the hard work of cleaning up the code and removing all globals :partying_face:

[BSchilperoort]

I've adressed all your comments @SarahAlidoost, and made some other changes I wanted to make.

You can now start the BMI mode without passing in a valid config:

./STEMMUS_SCOPE "" bmi

The config is then passed with initialize:

> Finished command. Select run mode: 
initialize "/path/to/cfg.txt"

[SarahAlidoost]

The config is then passed with initialize:

./STEMMUS_SCOPE "" initialize "/path/to/cfg.txt"

this command is not correct. It returns error:

Error using STEMMUS_SCOPE_exe
Too many input arguments.

MATLAB:TooManyInputs

[BSchilperoort]

Thanks for the review! I have committed your suggestions and addressed your comments.