feat: Support for % in ecconomy by remvoing the default: throw new In…

[Javarev1]

Support for % in ecconomy by remvoing the default: throw new InvalidModifierException() branch in the parser.

• (Percent support for /economy #6530)

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[mdcfe]

This change does not add support for % signs. There are several places where currency format symbols can be passed into formatting calls where % would be parsed as a placeholder and so cause hard-to-track-down exceptions elsewhere, both within and outside of EssentialsX's control, and so the safest option is to forbid the % sign.

Edit: it's not even clear what functionality this PR is trying to add. Please elaborate by filling out the PR template properly, as requested when you opened the PR.