Preserve SSH key passphrase on connection errors (#979)

* Update sshj to 0.30.0 and improve algorithm order

Updates sshj to 0.30.0, which brings support for rsa-sha2-* key types
and bugfixes related to RSA certificates and Android Keystore backed
keys.

Along the way, this improves the algorithm preferences to be consistent
with the Mozilla Intermediate SSH configuration (as far as possible,
given that most certificate types and some encryption algorithms are
not yet supported).

We also add "ext-info-c" to the kex algorithm proposal to work around
certain kinds of "user agent sniffing" that limits the support of
rsa-sha2-* key types.

* Preserve SSH key passphrase on connection errors

Co-authored-by: Harsh Shandilya <me@msfjarvis.dev>

app/src/main/java/com/zeapo/pwdstore/git/operation/GitOperation.kt

@@ -157,7 +157,6 @@ abstract class GitOperation(gitDir: File, internal val callingActivity: Fragment
             }
             is SshjSessionFactory -> {
                 callingActivity.getEncryptedPrefs("git_operation").edit {
-                        remove(PreferenceKeys.SSH_KEY_LOCAL_PASSPHRASE)
                         remove(PreferenceKeys.HTTPS_PASSWORD)
                     }
             }