Add a tutorial on integrating Galexie with RPC

[Shaptic]

This could be a good if the "user story" for this was something like "full history reingestion"

[johncanneto]

This might increase the points, but is it possible to capture this as a video tutorial?

[ElliotFriend]

Covered by two docs that landed after this was filed: docs/data/apis/rpc/admin-guide/data-lake-integration.mdx (#1673) and docs/data/indexers/build-your-own/galexie/admin_guide/full-history-exporting.mdx (#1795). The video-tutorial suggestion from the comments remains unaddressed — if that's still wanted, let's open it as its own scoped issue. Closing as completed.