flow_view_uses doesn't show uses in R6 methods

[moodymudskipper]

We have to define the logic but also decide how it will be represented.

There is no agreement on how to denominate a method from an R6 object created with my_R6$new(), though the method mentioned separately is usually described by $my_method() without a lhs.

Given that an R6 object that behaves as advised by the doc will create an object with a class spelled as its constructor, I think we might take the constructor's name between <> followed by the dollar and method, e.g. : <my_R6>$my_method()

We have to consider public and private, and we'll show them with the same syntax, also $initialize() stays this way, we don't show $new()