Multiline anonymous functions should forcibly have their `body` wrapped in `{ }`

[DavisVaughan]

\(x) if (is.na(x)) "CRAN" else cli::cli_fmt(cli::cli_text("{.field {x}} field in DESCRIPTION"))

Currently formatted as

\(x)
  if (is.na(x)) "CRAN" else
    cli::cli_fmt(cli::cli_text("{.field {x}} field in DESCRIPTION"))

I think in this case it should really be:

\(x) {
  if (is.na(x)) {
    "CRAN"
  } else {
    cli::cli_fmt(cli::cli_text("{.field {x}} field in DESCRIPTION"))
  }
}

We already planned to force multiline if/else to be wrapped in { } (it's related to #225 and tidyverse/style#240), but I think we should also apply this to function logic too.

i.e. if a user requested line break is already there before the body, or the whole thing can't fit on one line, then forcibly add { }. Because as soon as you add a second statement, you need them anyways.