refactor: Unify balances between wallet and SPV

[xdustinface]

We currently have AddressBalance in dash-spv and WalletBalance in key-wallet. They differ slightly with the SPV one considering instant locks. We should probably have a single balance structure in the wallet which covers everything and gets used from the SPV client.

rust-dashcore/dash-spv/src/types.rs

Lines 570 to 583 in b181584

	#[derive(Debug, Clone, PartialEq, Eq)]
	pub struct AddressBalance {
	/// Confirmed balance (6+ confirmations or InstantLocked).
	pub confirmed: dashcore::Amount,
	/// Unconfirmed balance (less than 6 confirmations).
	pub unconfirmed: dashcore::Amount,
	/// Pending balance from mempool transactions (not InstantLocked).
	pub pending: dashcore::Amount,
	/// Pending balance from InstantLocked mempool transactions.
	pub pending_instant: dashcore::Amount,
	}

rust-dashcore/key-wallet/src/wallet/balance.rs

Lines 11 to 19 in bad5230

	#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
	pub struct WalletBalance {
	/// Confirmed and mature balance (UTXOs with enough confirmations to be spendable)
	spendable: u64,
	/// Unconfirmed balance (UTXOs without confirmations)
	unconfirmed: u64,
	/// Locked balance (UTXOs reserved for specific purposes like CoinJoin)
	locked: u64,
	}