Generators: add initial set of tests #2037

Job	Run time
Build Phar on PHP: 8.0	25s
Coverage: 8.4 (Linux)	4m 15s
Coverage: 8.4 (Win)	3m 49s
Coverage: 5.4 (Linux)	25m 34s
Coverage: 5.5 (Win)	2m 16s
Coverage: 7.2 with custom ini settings (Linux)	5m 45s
PHP: 5.4 (Linux)	1m 15s
PHP: 5.5 (Linux)	7m 29s
PHP: 5.6 (Linux)	5m 56s
PHP: 7.0 (Linux)	1m 40s
PHP: 7.1 (Linux)	1m 46s
PHP: 7.2 (Linux)	1m 32s
PHP: 7.3 (Linux)	1m 9s
PHP: 7.4 (Linux)	50s
PHP: 8.0 (Linux)	51s
PHP: 8.1 (Linux)	47s
PHP: 8.2 (Linux)	1m 3s
PHP: 8.3 (Linux)	1m 6s
PHP: 8.4 (Linux)	43s
PHP: 8.5 (Linux)	56s
PHP: 5.5 (Win)	1m 7s
PHP: 5.6 (Win)	6m 0s
PHP: 7.0 (Win)	1m 37s
PHP: 7.1 (Win)	1m 42s
PHP: 7.2 (Win)	1m 41s
PHP: 7.3 (Win)	1m 4s
PHP: 7.4 (Win)	1m 0s
PHP: 8.0 (Win)	52s
PHP: 8.1 (Win)	1m 3s
PHP: 8.2 (Win)	55s
PHP: 8.3 (Win)	1m 2s
PHP: 8.4 (Win)	39s
PHP: 8.5 (Win)	59s
PHP: 5.5 with custom ini settings (Linux)	6m 54s
PHP: 7.0 with custom ini settings (Linux)	1m 22s
coveralls-finish	2s
	1h 37m 6s

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