The ChannelMonitor::get_claimable_balances and ChainMonitor::get_claimable_balances
methods provide a more straightforward approach to the balance of a channel, which
satisfies most use cases. The computation of AvailableBalances::balance_msat is
complex and originally had a different purpose that is not applicable
anymore.
Co-authored-by: Willem Van Lint <noreply@wvanlint.dev>