replace `mining_sv2::Target` with `bitcoin::Target`

[plebhash]

mining_sv2 provides a Target type that could be replaced with bitcoin::Target

there's references to mining_sv2::Target in many parts of the code (e.g.: channels_sv2), where this should also be replaced

[GitGab19]

As pointed out here, we should also get rid of the target_to_difficulty function we have in channels_sv2::target and start using the APIs coming from rust-bitcoin to do that.

[icarusmaximal]

should hash_rate_to_target from roles-logic-sv2::src::utils be modified to return Target instead of U256, or renamed to hash_rate_to_target_U256 ?

[Sansh2356]

@icarusmaximal are you working on this issue ?

[icarusmaximal]

@Sansh2356 yes.

[icarusmaximal]

@plebhash should i stick to migrate mining_sv2::Target only, or convert other types like U256 as well wherever possible e.g. pub max_target: U256<'decoder> to pub max_target: Target

here, max_target is an attribute of OpenExtendedChannel

[plebhash]

sorry for the late reply @icarusmaximal

I gave a quick look at #1950, and despite the current conflicts, it seems to be going in a good direction

should hash_rate_to_target from roles-logic-sv2::src::utils be modified to return Target instead of U256, or renamed to hash_rate_to_target_U256?

I see you went ahead and made channels_sv2::target::hash_rate_to_target return Target, and I think that was the right decision, given how this function is used across the crate.

it's important to note that roles_logic_sv2 is on the process of being deprecated, so I wouldn't worry about the duplicates of this function there.

@plebhash should i stick to migrate mining_sv2::Target only, or convert other types like U256 as well wherever possible e.g. pub max_target: U256<'decoder> to pub max_target: Target

here, max_target is an attribute of OpenExtendedChannel

we need every message definition to conform to the Sv2 Spec, and changing OpenExtendedMiningChannel.max_target to something other than U256 would violate that

[GitGab19]

Closed by #1950