Increases network read timeout to 5 minutes when sending a payment via HTTP

[NicolasFlamel1]

This change increases the network read timeout to 5 minutes when sending a payment via HTTP. This fixes sending payments to people using the Epic Cash Ledger hardware wallet app which can take up to a minute to create a bulletproof.

The 5 minute read timeout is only applied when sending a receive_tx request, and all other requests will still use the default read timeout. This avoids any unnecessary waiting when sending a payment since a check_version request always comes before a receive_tx request.

[who-biz]

Looks fine to me. Will review once focus shifts back to Ledger integrations.

We should test thoroughly to ensure that this does not affect regular network txs adversely.

[who-biz]

Ledger work on hold indefinitely. We'll see if their listing queue opens up in bull market. Also throwing around the idea of a more privacy-focused Ledger fork. But low priority atm.

Open for discussion if we wish to elevate to higher priority.