[JENKINS-75011] Use Apache Mina as ssh transport layer, remove trilead

[jmdesprez]

PR for JENKINS-75011

Mainly, the changes consist of:

• Create a SshClient where a connection is needed
• Replace Connection by ClientSession
• Replace SCPClient by CloseableScpClient
• use try-with-resource for Closeable resources
• Add ProxyCONNECTListener for the http proxy CONNECT
• Add PEMParser because Mina requires a KeyPair instead of a char[]

Testing done

I create this in draft mode because I'm still doing manual tests.

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