Add `==` definition of `ComposedOptic` and `IndexLens` from `Setfield` #534

Job	Run time
Documentation	1m 18s
Julia 1.6 - ubuntu-latest - x64 - pull_request	1m 9s
Julia 1.6 - windows-latest - x64 - pull_request	8m 38s
Julia 1 - ubuntu-latest - x64 - pull_request	1m 11s
Julia 1 - windows-latest - x64 - pull_request	1m 47s
Julia nightly - ubuntu-latest - x64 - pull_request	2m 29s
Julia nightly - windows-latest - x64 - pull_request	3m 12s
	19m 44s

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