Retry getting block date and price

[KirillLykov]

While using sys account add or sys sync I often get error Error: reqwest::Error { kind: Decode, source: Error("missing field id", line: 1, column: 187) }. It happens when get_block_date_and_price fails and because intermediate progress is not written to db, user has to restart the whole process from the begging.
This simple change adds retry logic around aforementioned call.

[mvines]

Thanks! get_block_date_and_price() internally touches two network resources:

1. Solana RPC endpoint: rpc_client.get_block_time() (

   sys/src/rpc_client_utils.rs

   Line 18 in 2092791

   let block_time = rpc_client.get_block_time(slot)?;

   )
2. Coingecko endpoint: coin_gecko::get_historical_price() (

   sys/src/coin_gecko.rs

   Line 109 in 2092791

   pub async fn get_historical_price(

   )

Are you seeing both (1) and (2) fail? My guess is that it's mostly (2)?
I'm thinking it might be better to push the retrying down a level to either (1) and/or (2), to be more network conscious and avoid retrying both (1) and (2) if it's only one of the two that's actually failing

[KirillLykov]

@mvines moved this code to get_price as suggested

[mvines]

Thanks! I'll add a follow-up commit about potentially moving the retry even lower. Ideally we'd do it from coin_gecko.rs and honour the exact http backoff time that their API is responding with one day