Add PHP docker image building #1114

Job	Run time
build-java (ubuntu-latest)	27s
build-ts (ubuntu-latest)	22s
build-python (ubuntu-latest)	22s
build-go (ubuntu-latest)	9s
build-dotnet (ubuntu-latest)	12s
feature-tests-python / test	1m 15s
feature-tests-ts / test	1m 52s
build-docker-images / build-php-docker-images	0s
feature-tests-go / test	2m 11s
feature-tests-dotnet / test	1m 10s
feature-tests-java / test	1m 48s
build-docker-images / build-go-docker-images / Build go docker image	2m 14s
build-docker-images / build-java-docker-images / Build java docker image	2m 37s
build-docker-images / build-dotnet-docker-images / Build cs docker image	1m 51s
build-docker-images / build-python-docker-images / Build py docker image	2m 7s
build-docker-images / build-ts-docker-images / Build ts docker image	2m 53s
	21m 30s

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