Convert the Surface Water Mass Transformation example to be model-agn…

…ostic (#402)

* reviewed agnostic SWMT on the correct recipes fork

* split into functions, model agnostic

* got an error

* specify file saving path

* now paths are good

* remove custom dirs + cleanup

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Co-authored-by: Wilton Filho <wf4500@gadi-login-06.gadi.nci.org.au>
Co-authored-by: Navid C. Constantinou <navidcy@users.noreply.github.com>
Co-authored-by: julia-neme <j.neme@unsw.edu.au>