CanIgnoreReturnValueSuggester should not warn on Swing cell renderer implementations

ErrorProne 2.15.0 introduced `CanIgnoreReturnValueSuggester`.

Most warnings it raised were legit, but one very common case which wasn't was on Swing cell renderers:
* `ListCellRenderer#getListCellRendererComponent`
* `TableCellRenderer#getTableCellRendererComponent`
* `TreeCellRenderer#getTreeCellRendererComponent`

Quite commonly, a Swing cell renderer is implemented by subclassing a component, so many implementations do return `this`. However, the implementation is free to change at any point as the method contract does not say that it must return `this` (and some implementations do not), so there is no guarantee that ignoring the return value is safe. Rather, I'd like to annotate these with something else saying that you can't ignore it, but I don't know whether such an annotation exists.

We suppressed all the warnings, but this could be a reasonable case for not getting the warning in the first place.