Role restrictions for Server Store

[isidar#0]

(Idea prompted by post in #help-and-support by NicholasStrider#6814 : https://discord.com/channels/173184118492889089/173184213862973440/855263278174961665 )

Be able to restrict server store usage by a role, or to require a role to be able to access the server store. 
The potential use would be for communities that may want to have some freedom over who can buy roles, but know some will abuse it or to give people the option to unlock channels after they've spent some time in the server. Such as game politics preventing the jerk from being banned, but not wanting them to have access to roles granting more freedom. Or giving the ability to buy access to Off Topic channels only after a member has "proven their worth" in the normal ones.

It is possible to block access to all the stores, but it doesn't feel right to block access to the Global store nor event stores.