Add self-update functionality #428

Job	Run time
static-analysis	21s
coding-standards	35s
unit-tests (ubuntu-latest, 8.1)	2m 13s
unit-tests (ubuntu-latest, 8.4)	2m 5s
unit-tests (ubuntu-latest, 8.2)	2m 42s
unit-tests (windows-latest, 8.3)	6m 38s
unit-tests (windows-latest, 8.1)	5m 49s
behaviour-tests (ubuntu-latest, 8.3)	1m 17s
unit-tests (windows-latest, 8.4)	5m 56s
behaviour-tests (ubuntu-latest, 8.1)	1m 10s
behaviour-tests (windows-latest, 8.4)	3m 31s
unit-tests (windows-latest, 8.2)	5m 52s
behaviour-tests (windows-latest, 8.2)	3m 28s
behaviour-tests (ubuntu-latest, 8.4)	1m 12s
behaviour-tests (ubuntu-latest, 8.2)	1m 23s
unit-tests (ubuntu-latest, 8.3)	2m 16s
behaviour-tests (windows-latest, 8.3)	3m 34s
behaviour-tests (windows-latest, 8.1)	3m 35s
build-phar / build-phar (ubuntu-latest, 8.1)	19s
	53m 56s

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