[Python] Enhancements to Cache instrumentation

[antonpirker]

We want to improve our instrumentation of caches. For this we want to have the following spans created when caches are accessed:

• <span op="cache.get_item" data.cache.hit="true/false" data.cache.item_size="123">
• <span op="cache.set_item" data.cache.item_size="123">

For details about the data that should be added to those spans see the linked sub issues.

The also the mockups here: getsentry/sentry#68265

• Caching module update for DjangoIntegration #2964
• Caching module update for RedisIntegration #2965
• New Memcached caching module #2966

[antonpirker]

The work has been done in the linked umbrella PRs (see the mentioned PRs in them to see the actual code changes)