Make spaces_left_parentheses_linter more robust when determining ( type

[saurfang]

Currently spaces_left_parentheses_linter contains false negatives when it comes to

for(i in seq_along(1:10)) { }

where if, for, while blocks could contain function calls.

It seems to me that we can improve this linter by stricter checking on the type of ('s owner. Previously if the line has any function calls, we completely let it go.

I have also incorporated the improved linter's suggestions in this PR. Hope that is okay.

Finally I'm not very familiar with this package yet. So definitely let me know if you see any concerns or potential improvements of my PR.

[jimhester]

Maybe change this to

last_type <- tail(terminal_types, n = 1)

Which might make it more explicit so a comment is unnecessary.

[saurfang]

Thanks for the suggestion @jimhester. I have made corresponding changes. I have also added ']' to the whitelist per #75, which I think makes sense and is relevant to this PR improving robustness of this particular linter. Let me know if you have any other thoughts or would like me to rebase this PR.

[jimhester]

Looks great, thanks!