Fix matching of pubkeys to key algorithms (#607)

* Fix matching of pubkeys to key algorithms

Allow all configured key algorithms for pubkey authentication, even if
these algorithms are not supported as host key algorithms by the
server.

Preference is given to the modern rsa-sha2-* signature algorithms if
the server indicates support for them as host keys signature
algorithms.

* Replace Boolean with primitive boolean

* Add integration tests for ecdsa-sha2-nistp384/521

* Remove redundant import

* Clean up Transport interface

Co-authored-by: Jeroen van Erp <jeroen@hierynomus.com>

src/itest/groovy/com/hierynomus/sshj/IntegrationSpec.groovy

@@ -77,6 +77,8 @@ class IntegrationSpec extends IntegrationBaseSpec {
         "id_ed25519_opensshv1_protected" | "sshjtest"
         "id_rsa" | null
         "id_rsa_opensshv1" | null
+        "id_ecdsa_nistp384_opensshv1" | null
+        "id_ecdsa_nistp521_opensshv1" | null
     }
 
    def "should not authenticate with wrong key"() {