Polish Maven metadata; support to build & test w/o access to the internet #136

Job	Run time
maven_bundle_url	37s
pre_commit	34s
build (ubuntu-latest)	3m 35s
build (windows-latest)	2m 27s
build (macos-latest)	3m 2s
unit-it-mp (ubuntu-latest)	2m 9s
isolate-it (ubuntu-latest)	1m 58s
unit-mp (ubuntu-latest)	2m 4s
unit-cp (ubuntu-latest)	36m 10s
unit-mp (macos-latest)	1m 37s
unit-cp (windows-latest)	1h 17m 43s
unit-it-mp (macos-latest)	1m 37s
unit-it-mp (windows-latest)	4m 45s
unit-cp (macos-latest)	36m 48s
integration (ubuntu-latest, test_jbang_integration.py)	1m 51s
integration (macos-latest, test_jbang_integration.py)	1m 45s
integration (ubuntu-latest, test_maven_plugin.py)	1m 59s
unit-mp (windows-latest)	3m 7s
integration (macos-latest, test_maven_plugin.py)	1m 58s
integration (windows-latest, test_jbang_integration.py)	2m 4s
integration (ubuntu-latest, test_gradle_plugin.py)	1m 55s
integration (macos-latest, test_gradle_plugin.py)	1m 57s
integration (windows-latest, test_maven_plugin.py)	2m 4s
integration (windows-latest, test_gradle_plugin.py)	2m 8s
	3h 15m 54s

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