Add preference to always hide script field.

[Petethegoat]

Replicates manually putting the [HideScriptField] attribute on all monobehaviours.

I haven't updated docs - it may be good to mention this setting on the attribute page (https://annulusgames.github.io/Alchemy/articles/en/attributes/hide-script-field.html) and maybe update https://annulusgames.github.io/Alchemy/images/img-project-settings.png that shows the settings screen.

Thanks.

Also, I changed the FindProperty() calls in AlchemySettings.cs to use nameof(field) instead of strings. Not related to the functionality at all, sorry.