feat: Allow admin done permission to override requiring plot complexity calculation

[MrJoshuaT]

Overview

Let admins always be able to set plots as done

Description

The permission plots.admin.command.done already exists but is only used to check if you have plot perms, it's very useful to allow admins with the permissions to not require doing plot calculations.

Also removed PlotSquared.platform().expireManager() == null condition on same line because it can never return null.

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