Request JSONs need to be pre-processed to prefix bytes with leading `0x` if not present

[xearl4]

With chia-blockchain moving to chia_rs, bytes values parsed from JSON are now enforced to have a leading 0x: https://github.com/Chia-Network/chia_rs/blob/main/crates/chia-protocol/src/bytes.rs#L97-L101. According to Chia-Network/chia-blockchain#13623, this enforcement is the expected and desired behaviour.

The Chia Pool Protocol 1.0 specification, however, allows bytes to be sent without leading 0x: "All bytes values are encoded as hex with optional 0x in front" (https://github.com/Chia-Network/pool-reference/blob/main/SPECIFICATION.md#https-endpoints-summary).

There are farmer implementations in the wild which send some values without a 0x prefix.

Thus, parsing of all JSON request payloads (PostFarmerRequest, PutFarmerRequest, and PostPartialRequest) needs to be adjusted to pre-process the JSON payload and prepend 0x in bytes field where the 0x is not present.