geyser: stream all accounts state outside of startup stage

[fanatid]

Problem

Right now if somebody wants to build an indexer based on geyser plugin they need to create a custom plugin and can't use gRPC plugin because geyser stream all accounts state only on the startup stage and it's not possible to get it later. With streaming all accounts it would be possible to create read layers outside of instance where node work.

Proposed Solution

agave:

• stream all accounts by request (set is_startup to true?)
• provide access to the bank (see Proof of Concept: Add update_bank to Geyser interface solana-labs/solana#32094), with bank it's possible to do much more than just stream all accounts
• ?

outside:

• stream all accounts on startup to some storage and update it with new accounts in the loop (full data duplication)

cc @lijunwangs