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

[sunxd3]

Fix https://github.com/JuliaObjects/Accessors.jl/issues/144 Pretty much copy and paste

[sunxd3]

Looks like Aqua is not happy with the == for CompsedOptic, which is essentially defining for ComposedFunction. Not sure what to do here.

[aplavin]

Also makes sense to add these equality methods to other optics defined in the file: eg DynamicIndexLens and Recursive.

[sunxd3]

Also I just realize adding equality for DynamicIndexLens is tricky, because the f field is anonymous function like collection -> firstindex(collection), which makes equality tests generally impossible. Recursive is similar as Descent can be anonymous function.