Fix formatter issues revealed during upgrade to scalameta 4.7.0

[kitbellew]

While attempting to upgrade to the most recent version of scalameta, one which contains additional trees containing argument and parameter clauses in various contexts, a number of possibly rare bugs were discovered, mainly in the portions of the code which attempted to identify locations of those argument/parameter clauses (even though they belonged to the entire encompassing expression).

Let's fix them before upgrading to sm 4.7.0.