Refactor Rav Request

[gusinacio]

Problem statement
Currently, the Rav Request system is not stable, any failure causes problems in the whole system.

The refactor between tap-core and tap-agent seems necessary to improve reliability, readability and maintainability.

[calinah]

this error is related

2024-09-19T20:15:10.486623Z DEBUG indexer_tap_agent::agent::sender_account: Total fee greater than the trigger value. Triggering RAV request, total_fee: 3044480420616669893, trigger_value: 2500000000000000000
    at tap-agent/src/agent/sender_account.rs:578
    in ractor::actor::Actor with id: "0.1", name: "0xDDE4cfFd3D9052A9cb618fC05a1Cd02be1f2F467"

  2024-09-19T20:15:10.486641Z ERROR indexer_tap_agent::agent::sender_allocation: Can't trigger rav request until Instant { tv_sec: 1262165, tv_nsec: 167912880 } (backoff)
    at tap-agent/src/agent/sender_allocation.rs:264
    in ractor::actor::Actor with id: "0.35", name: "0xDDE4cfFd3D9052A9cb618fC05a1Cd02be1f2F467:0xdE477aFB87B72E6CA7447d6B35254771088521Ce"

It seems the error indicates that too many RAV requestes are being requested at once and there's an enforced backoff to slow things down