Add additional benchmarks for "updates"

[apelisse]

We currently were mostly benchmarking creation, apply but not updates,
nor any updates across versions. These new tests show that updates are
extremely expensive for objects that have big "atomic" values because
the comparison is pretty slow.

pkg: sigs.k8s.io/structured-merge-diff/merge
BenchmarkDeducedSimple-12                             	   10000	    102086 ns/op	   33768 B/op	     570 allocs/op
BenchmarkDeducedNested-12                             	    3000	    375675 ns/op	  103168 B/op	    1910 allocs/op
BenchmarkDeducedNestedAcrossVersion-12                	    3000	    407410 ns/op	  106689 B/op	    1978 allocs/op
BenchmarkLeafConflictAcrossVersion-12                 	   20000	     91036 ns/op	   31151 B/op	     505 allocs/op
BenchmarkMultipleApplierRecursiveRealConversion-12    	    1000	   1604863 ns/op	  508926 B/op	    5180 allocs/op
BenchmarkOperations/Pod/Create-12                     	   10000	    106094 ns/op	   17622 B/op	     255 allocs/op
BenchmarkOperations/Pod/Apply-12                      	    5000	    282660 ns/op	   58181 B/op	     710 allocs/op
BenchmarkOperations/Pod/Update-12                     	   10000	    192032 ns/op	   26522 B/op	     420 allocs/op
BenchmarkOperations/Pod/UpdateVersion-12              	    5000	    277914 ns/op	   34416 B/op	     565 allocs/op
BenchmarkOperations/Node/Create-12                    	   10000	    154485 ns/op	   26362 B/op	     283 allocs/op
BenchmarkOperations/Node/Apply-12                     	    3000	    476571 ns/op	   98132 B/op	     981 allocs/op
BenchmarkOperations/Node/Update-12                    	    5000	    292993 ns/op	   37745 B/op	     467 allocs/op
BenchmarkOperations/Node/UpdateVersion-12             	    3000	    447654 ns/op	   48123 B/op	     631 allocs/op
BenchmarkOperations/Endpoints/Create-12               	  200000	     11834 ns/op	    2860 B/op	      45 allocs/op
BenchmarkOperations/Endpoints/Apply-12                	    2000	    910033 ns/op	   46889 B/op	    1076 allocs/op
BenchmarkOperations/Endpoints/Update-12               	     200	   7172467 ns/op	    4484 B/op	      77 allocs/op
BenchmarkOperations/Endpoints/UpdateVersion-12        	     100	  14381702 ns/op	    5104 B/op	      89 allocs/op
BenchmarkOperations/CustomResourceDefinition/Create-12         	    1000	   1288391 ns/op	  118017 B/op	    1624 allocs/op
BenchmarkOperations/CustomResourceDefinition/Apply-12          	     500	   3417275 ns/op	  409462 B/op	    4961 allocs/op
BenchmarkOperations/CustomResourceDefinition/Update-12         	     100	  10698995 ns/op	  139111 B/op	    1960 allocs/op
BenchmarkOperations/CustomResourceDefinition/UpdateVersion-12  	     100	  18946980 ns/op	  159134 B/op	    2276 allocs/op

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: apelisse

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[apelisse]

cc @jennybuckley @lavalamp

[lavalamp]

/lgtm