Add %GROUP_META_XXXX% and %USER_META_XXXX% placeholder

[blairwilson]

Is your feature request related to a problem? Please describe.
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I need a placeholder that reads a users Meta values for easier addition of extra prefixes from certain plugins that don't use the typical prefix.1.X way of adding prefixes.

Describe the solution you'd like
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A placeholder that reads either group or user meta and shows the value of the meta key
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PlaceholderAPI but does not offer LuckPerms support for Sponge

[OllieMartin]

I think that for now this is beyond the scope of the plugin. Have you considered: https://ore.spongepowered.org/Nurdism/LuckHolders

I won't rule out adding it, however I think a solution might already exist in the above plugin. I have used luckperms placeholders in Sponge before with PAPI.