Support OpenSSH with certificate user authentication

[AliveDevil]

Feature 8.0 mentions support for SSH certificates due to support in SSHJ (v0.32.0), but requires setup to work properly.
In 8.0 Public Key Authentication is used as

cyberduck/ssh/src/main/java/ch/cyberduck/core/sftp/auth/SFTPPublicKeyAuthentication.java

Line 96 in 6584993

provider.init(new InputStreamReader(identity.getInputStream(), StandardCharsets.UTF_8), new PasswordFinder() {

We'd need to forward the absolute file path to SSHJ in order to get SSH certificates to work properly, like:

public static File getPublicKeyFile(File privateKeyFile) {
    File pubKey = new File(privateKeyFile + "-cert.pub");
    if (!pubKey.exists()) {
        pubKey = new File(privateKeyFile + ".pub");
    }
    if (pubKey.exists()) {
        return pubKey;
    }
    return null;
}

https://github.com/hierynomus/sshj/blob/ff4a4774bd1e3d45e9e796c2b17ef835e7e6d67f/src/main/java/com/hierynomus/sshj/userauth/keyprovider/OpenSSHKeyFileUtil.java#L32-L41

or, based on contract, call initPublicKey after init:

https://github.com/hierynomus/sshj/blob/ff4a4774bd1e3d45e9e796c2b17ef835e7e6d67f/src/main/java/net/schmizz/sshj/userauth/keyprovider/OpenSSHKeyFile.java#L88-L92

[dkocher]

Reverted in 59e1843.