SnapCraft support

[kerner1000]

I'm submitting a…

• [ ] bug report
• [X] feature request
• [ ] other

Short description of the issue/suggestion:

It would be nice to have support to build a SnapCraft snap.

[fvarrui]

Currently researching about SnapCraft

[fvarrui]

Snap package manually built with success for a sample project using next config file (target/snap/snapcraft.yaml):

name: helloworldmaven
base: core22
version: '1.0.0'
summary: Hello world app packaged with JavaPackager
description: |
  This is HelloWorld description.

grade: devel # must be 'stable' to release into candidate/stable channels
confinement: devmode # use 'strict' once you have the right plugs and slots

apps:
  HelloWorldMaven:
    command: HelloWorldMaven
    extensions: [ gnome ]
    environment:
      JAVA_HOME: $SNAP/jre
      PATH: $JAVA_HOME/jre/bin:$PATH

parts:
  app:
    plugin: dump
    source: ./HelloWorldMaven
    source-type: local

[fvarrui]

Work in progress on issue-229.