Support the `projection` parameter in `getObject` #3172

Job	Run time
build	26s
lint	17s
staticcheck	48s
tests (macos/go-1.21-amd64)	52s
tests (ubuntu/go-1.21-386)	13s
tests (ubuntu/go-1.21-amd64)	50s
tests (windows/go-1.21-386)	2m 3s
tests (windows/go-1.21-amd64)	2m 11s
tests (macos/go-1.22-amd64)	56s
tests (ubuntu/go-1.22-386)	35s
tests (ubuntu/go-1.22-amd64)	53s
tests (windows/go-1.22-386)	7m 13s
tests (windows/go-1.22-amd64)	2m 8s
test-python-example	27s
test-gsutil-example	37s
test-node-example	12s
test-go-example	33s
test-dotnet-example	14s
test-ruby-example	16s
test-scala-example	43s
test-java-example	20s
test-cpp-example	2m 20s
test-curl-example	11s
test-curl-both-scheme-default-ports-example	10s
test-curl-both-scheme-non-default-ports-example	10s
unblock-pr	1s
	25m 39s

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