Cannot connect GNMI device using PEM format key

[ihrasko]

Describe the bug
GNMI app is not able to use PEM encoded client keys. We have to manually transform them to RSA format.

Branch
main

To Reproduce

1. Use the script lighty-modules/lighty-gnmi/lighty-gnmi-connector/src/main/scripts/generate_certs.sh to generate client keys for GNMI connection over TLS.
2. Run GNMI simulated device with configuration to use newly generated certs and keys.
3. Add newly generated certs and keys to controller's keystore via RESTCONF.

For previous steps please follow https://github.com/PANTHEONtech/lighty/blob/main/lighty-examples/lighty-gnmi-community-restconf-app/README.md.

4. Add new GNMI device to topology with correctly set keystore-id.
5. Device is not connected - we are even missing the connection status in GNMI topology.

Expected behavior
Device is successfully connected with PEM encrypted key.

[ihrasko]

The logs:

DataTreeChangeListenerAdapter{listener=io.lighty.gnmi.southbound.listener.GnmiNodeListener@6d53245f}
java.lang.ClassCastException: class org.bouncycastle.asn1.pkcs.PrivateKeyInfo cannot be cast to class org.bouncycastle.openssl.PEMKeyPair (org.bouncycastle.asn1.pkcs.PrivateKeyInfo and org.bouncycastle.openssl.PEMKeyPair are in unnamed module of loader 'app')
        at io.lighty.aaa.util.AAAConfigUtils.decodePrivateKey(AAAConfigUtils.java:92)
        at io.lighty.gnmi.southbound.device.session.security.KeystoreGnmiSecurityProvider.getKeyPair(KeystoreGnmiSecurityProvider.java:103)
        at io.lighty.gnmi.southbound.device.session.security.KeystoreGnmiSecurityProvider.getSecurityWithCertificates(KeystoreGnmiSecurityProvider.java:86)
        at io.lighty.gnmi.southbound.device.session.security.KeystoreGnmiSecurityProvider.getSecurityFromKeystoreId(KeystoreGnmiSecurityProvider.java:75)
        at io.lighty.gnmi.southbound.device.session.security.KeystoreGnmiSecurityProvider.getSecurity(KeystoreGnmiSecurityProvider.java:47)
        at io.lighty.gnmi.southbound.device.connection.DeviceConnectionInitializer.initConnection(DeviceConnectionInitializer.java:66)
        at io.lighty.gnmi.southbound.device.connection.DeviceConnectionManager.connectDevice(DeviceConnectionManager.java:90)
        at io.lighty.gnmi.southbound.listener.GnmiNodeListener.connectNode(GnmiNodeListener.java:107)
        at io.lighty.gnmi.southbound.listener.GnmiNodeListener.onDataTreeChanged(GnmiNodeListener.java:75)
        at org.opendaylight.mdsal.binding.dom.adapter.BindingDOMDataTreeChangeListenerAdapter.onDataTreeChanged(BindingDOMDataTreeChangeListenerAdapter.java:56)
        at org.opendaylight.controller.cluster.datastore.DataTreeChangeListenerActor.dataTreeChanged(DataTreeChangeListenerActor.java:97)
        at org.opendaylight.controller.cluster.datastore.DataTreeChangeListenerActor.handleReceive(DataTreeChangeListenerActor.java:55)
        at org.apache.pekko.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:33)
        at org.apache.pekko.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:29)
        at scala.PartialFunction.applyOrElse(PartialFunction.scala:214)
        at scala.PartialFunction.applyOrElse$(PartialFunction.scala:213)
        at org.apache.pekko.japi.pf.UnitCaseStatement.applyOrElse(CaseStatements.scala:29)
        at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:269)
        at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:270)
        at org.apache.pekko.actor.Actor.aroundReceive(Actor.scala:547)
        at org.apache.pekko.actor.Actor.aroundReceive$(Actor.scala:545)
        at org.apache.pekko.actor.AbstractActor.aroundReceive(AbstractActor.scala:229)
        at org.apache.pekko.actor.ActorCell.receiveMessage(ActorCell.scala:590)
        at org.apache.pekko.actor.ActorCell.invoke(ActorCell.scala:557)
        at org.apache.pekko.dispatch.Mailbox.processMailbox(Mailbox.scala:280)
        at org.apache.pekko.dispatch.Mailbox.run(Mailbox.scala:241)
        at org.apache.pekko.dispatch.Mailbox.exec(Mailbox.scala:253)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)

[ihrasko]

The output of GNMI topology:

curl --request GET 'http://127.0.0.1:8888/restconf/data/network-topology:network-topology/topology=gnmi-topology' | python3 -m json.tool

{
    "network-topology:topology": [
        {
            "topology-id": "gnmi-topology",
            "node": [
                {
                    "node-id": "gnmi-simulator",
                    "gnmi-topology:connection-parameters": {
                        "port": 10161,
                        "credentials": {
                            "username": "admin",
                            "password": "admin"
                        },
                        "host": "127.0.0.1",
                        "keystore-id": "keystore-id-4"
                    },
                    "gnmi-topology:extensions-parameters": {
                        "gnmi-parameters": {
                            "use-model-name-prefix": true
                        }
                    }
                }
            ]
        }
    ]
}

[ihrasko]

Manual workaround: #2356.