remove `ContactsService`

[tomholub]

We could find a new home for this method, and then delete ContactsService.

Originally posted by @tomholub in #1165 (comment)

[tomholub]

[tomholub]

these methods provide no value, since each method is just a one-liner. The consumers of these can be refactored to use the underlying methods directly.

extension ContactsService: ContactsProviderType {
    func findLocalContact(with email: String) async throws -> RecipientWithSortedPubKeys? {
        return try await localContactsProvider.searchRecipient(with: email)
    }

    func searchLocalContacts(query: String) throws -> [String] {
        try localContactsProvider.searchEmails(query: query)
    }

    func fetchContact(with email: String) async throws -> RecipientWithSortedPubKeys {
        let recipient = try await pubLookup.lookup(email: email)
        try localContactsProvider.updateKeys(for: recipient)
        return recipient
    }
}

extension ContactsService: PublicKeyProvider {
    func retrievePubKeys(for email: String) throws -> [String] {
        try localContactsProvider.retrievePubKeys(for: email)
    }

    func removePubKey(with fingerprint: String, for email: String) throws {
        try localContactsProvider.removePubKey(with: fingerprint, for: email)
    }
}

The only method that's a bit more interesting is

    func fetchContact(with email: String) async throws -> RecipientWithSortedPubKeys {
        let recipient = try await pubLookup.lookup(email: email)
        try localContactsProvider.updateKeys(for: recipient)
        return recipient
    }

which we could move into PubLookup and call it fetchRemoteUpdateLocal. That would make PubLookup depend on LocalContactsProviderType.