Feature Request: UI to clear Redis cache

[crayolakat]

Problem
Sometimes old/wrong values in the Redis cache lead to unexpected behavior. E.g.: I changed the permissions of somebody's account via an SQL command, and the Redis cache didn't get updated so they aren't getting the right permissions when using Spoke. To solve these issues, we currently have to log into where Redis is hosted and run some manual commands to delete the cache.

Solution
A UI feature in Spoke to clear different cache prefixes that can cause problems when the data in there becomes out-of-date. E.g.: texterroles, optouts

Context
Currently the "Clear cached organization and extension caches" button in Spoke admin settings doesn't clear all problematic cache prefixes, including texterroles and optouts.

Slightly related issue: https://github.com/MoveOnOrg/Spoke/issues/2163