fix: proper private account_id check

[fkrause98]

Description

While testing the new public account retrieval flow in the miden-client, we stumbled upon an error when requesting details of a network account.

This PR simply changes the check to allow the retrieval of details for public and network accounts.

[bobbinth]

Looks good! Thank you!

[Mirko-von-Leipzig]

Just to understand this properly. Is the problem that Account::is_public() returns false for network accounts? And this is because it is short-hand for something like

enum AccountType {
    Private,
    Public,
    Network,
}

fn is_public(self: &AccountType) -> bool {
    matches!(self, AccountType::Public)
}

We really need to work on our naming schemes if that's the case. Or remove these helpers.

[igamigo]

Just to understand this properly. Is the problem that Account::is_public() returns false for network accounts?

Yeah, this was pretty much it