New lint equivalency test: including/excluding '{' in functions, if/else/while/repeat

[MichaelChirico]

We've seen occasionally lints that hard-code the assumption of tidyverse style where { is almost always required, but lints might also be emitted for non-tidyverse style like:

lapply(y, function(x)
  x)
# ^ unnecessary_lambda_linter()

if (A & B)
  TRUE
# ^ vector_logic_linter()

(haven't tested whether the above lints, just illustrating my point about code that usually has '{' that needn't always do so)