database: add redb-memory backend

[hinto-janai]

Part 17

#96 <- Previous Next -> #98

• Adds a new redb-memory feature flag that uses the same code from src/backend/redb, except that it uses redb::backend::InMemoryBackend instead which resides completely in memory instead of on disk

[SyntheticBird45]

What would be the use case exactly ?

[hinto-janai]

Solely for debugging and as a benchmark control group I guess.

It's only a few lines to add but it's not 100% necessary.

[Boog900]

Yeah this is small enough and could be useful, would be cool to have all back ends configurable at runtime