Feature: Option to choose positive or negative sign convention for tensile and compressive stress

[kikifadilah31]

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Feature Request

For some users, sign conventions may vary. For example, users who are familiar with structural analysis software such as SAP2000 often interpret tensile stress as positive and compressive stress as negative. It may be worth considering adding an option to support this convention in the package. Thank you.

[github-actions]

Thanks for opening your first issue in sectionproperties 🙌 Pull requests are always welcome 😉