Update SSH library for secured remote consoles / Support for Ed25519 keys is missing

Up to now StatET is using JCraft JSch as SSH library for secured remote consoles. JSch is shipped and integrated by the Eclipse IDE. But it is no longer active maintained and does not support new Ed25519 keys.

• There is a currently maintained fork of JSch at GitHub.
  • Pro: unchanged API
  • Cons: it is not a simple replacement because the integration in the Eclipse IDE is missing; no Eclipse plugin is using it
• Apache Mina SSHD is a currently maintained SSH library
  • Pro: clear IP; used by JGit/Egit -> consistent user experience
  • Cons: no integration in the Eclipse IDE; API by JGit/Egit is limited

Tasks:

• Add abstract SSH layer to seperate SSH implementation from different bundles using SSH.
• Add support for Apache Mina SSHD as SSH library.
• Update/Check prereq.ids / NOTICE.
• Test:
  • Startup
  • Connect
  • RJ-Auth
  • Browse Sessions
  • App-Browser
  • Ed25519 key
  • Installation
• Docu settings.