provider: flush the store cache when providers are loaded/unloaded.

provider: flush the store cache when providers are loaded/unloaded.

When the providers change, the method cache needs to be flushed.  This also
impacts the cache is full partial flushes and the algorithm flushing by ID.

A new function is introduced to clear all of the operation bits in all
providers in a library context.

Fixes #15032

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15042)