avoid_function_literals_in_foreach_calls should accept expression body

[yelliver]

Describe the issue This rule https://dart-lang.github.io/linter/lints/avoid_function_literals_in_foreach_calls.html

To Reproduce Having this line of code (and got the waring violating the rule): people.forEach((person) => person.foo(param));

Expected behavior I think the above code still satisfies the principle of the rule because when using expression body, it is just 1 line

[srawlins]

The rule is not in place to encourage shorter code, but to encourage more performant code (I think) which doesn't involve unnecessary closures. In any case it's more idiomatic (https://dart.dev/guides/language/effective-dart/usage#avoid-using-iterableforeach-with-a-function-literal).

Of course there isn't documentation on the lint rule explaining this; I'll leave it open for now to support adding such documentation.

[lrhn]

(We could also lobby for the formatter/style guide to accept for (var person in people) person.foo(param); on one line, like we do for single-line ifs.)