get logs from cache

[shunjizhan]

Context

Currently when no subql is presented, we can't get logs at all.

However, for most local testing scenarios, such as chopsticks acala fork testnet, it's deployed as a "light stack" without subql. In these cases we usually focus on recent txs/logs/blocks, and don't need to fetch very old data. So It would be nice if we can get (recent) logs without subql

Change

If no subql, check if the cache contains all required blocks:

• if so fetch logs from the cache
• else throw error (should throw explicit error instead of returning false empty)

Now we can start eth rpc with big cache size to simulate a fully functional stack to test more conveniently

fix #901

Test

Added tests to make sure it can still getlogs without subql