Contributes to ElementsProject#564 by providing an interface for mapLocalHost
through net -> node interface -> clientModel. Later this value can be
read by GUI to show the local addresses.

Adds a new row to the Node Window (debugwindow.ui)
under the Network section which shows the LocalAddresses.

fixes ElementsProject#564

189c987 Showing local addresses on the Node Window (Jadi)
a5d7aff net: Providing an interface for mapLocalHost (Jadi)

Pull request description:

  This change adds a new row to the Node Window (debugwindow.ui)
  under the Network section which shows the LocalAddresses.

  fixes ElementsProject#564

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ACKs for top commit:
  pablomartin4btc:
    re-ACK 189c987
  furszy:
    utACK 189c987

Tree-SHA512: 93f201bc6d21d81b27b87be050a447b841f01e3efb69b9eca2cc7af103023d7cd69eb5e16e2875855573ef51a5bf74a6ee6028636c1b6798cb4bb11567cb4996