Subclasses of Select don't accept `required` parameter

[LeviPesin]

Summary

Subclasses of Select don't accept required parameter, including UserSelect/RoleSelect/MentionableSelect/ChannelSelect. It is useful for using in modals.

Also, I thought these selects should have .required=True by default, like Select, but at least for ChannelSelect this isn't true.

Minimal Reproducible Code

ChannelSelect(required=True) -- this doesn't work
Select(required=True) -- this works

ChannelSelect().required -- False
Select().required -- True

Checklist

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[Soheab]

Fixed with #10307